In this chapter, the people travel onwards into the desert, the LORD continues to provide for their needs and the Sabbath is instituted for Israel.
Starting in verse 3, the people begin complaining again. It's amazing to see the revisionism that happens when a group of people are unhappy with their circumstances. In chapter 1 we see the "groaning" of the Israelites under the burden of the Egyptians, we see all of their newborn sons being killed, and now that the Israelites have freedom from this they wish they could go back and sit "by the pots of meat". There is a type of attitude that a person can take where they always complain about what's happening now: one forgets the difficulties of the past and only remembers the good, while only seeing the difficulties of the present and ignoring how things have improved. Clearly the Israelites have this attitude, because it seems no matter where they go, they collectively focus only on their problems for the moment while longing for whatever meager blessings they once had.
If there's one story this reminds me of most, it's when Esau sold his birthright to Jacob for a bowl of red stew and some bread. The common theme here is abandoning spiritual heritage or purpose in exchange for food, i.e. material comfort. In Genesis 25, it says that "Esau despised his birthright" by selling it to Jacob for a temporary comfort; hungry as he might have been, Esau obviously wouldn't have died if he had waited and gone to get food somewhere else. Here, the people are longing to return to Egypt for the temporary comfort of food, even if it comes with the price of slavery and spurning forever their destiny in the promised land.
Just the same, there is a food problem so God miraculously provides meat and a strange type of bread to the people, to complement the water he provided in the last chapter. This is the miracle of the wilderness journey. Just as the miracles of the plagues brought them out of Egypt, now the miracles have altered to fit their circumstances to provide for them physically.
The bread is given to them every day, and only a day's bread is given. On the day before the Sabbath, they are given two days' worth of bread. It is daily sustenance that comes directly from God. Like so many things in the OT, it is a physical sign or miracle that has spiritual implications that will be fleshed out later.
And the Sabbath is instituted by Moses. This chapter contains the first instance of the word "Sabbath" in the OT. There has been a prior reference to the "seventh day", however, all the way back in Genesis 2:2-3 which basically said that the seventh day is sacred and that God rested on the seventh day, but it did not at that time mandate God's people to also rest on the seventh day. After that, there was no mention at all of the patriarchs observing the Sabbath and no mention of the Israelites observing the Sabbath while they were in Egypt.
Now we discover that the Israelites are to rest on the seventh day, in emulation of God's resting on the seventh day. As we observe even in this chapter, holding the Sabbath proves difficult for the Israelites because they desire to work through it for personal gain. In this chapter, they go out seeking manna on the Sabbath and they do not find any, because there is no gain to be found by breaking God's commands. Later, we will see other instances of Israelites doing work on the Sabbath like gathering wood or selling products.
The Sabbath certainly has a practical dimension to it, in terms of giving the people a chance (well, a command) to rest and recuperate at the end of a week. It has also historically been the day when Jews go to worship God in a synagogue or to hear the word of God. I also feel like obeying the Sabbath is meant to give the people of God an opportunity to reconnect with life from before the curse of Adam. Remember that one of the core elements of Adam's curse is that his work would be a burden, that by the sweat of his brow he would produce crops from the earth. We see this in the Israelite attitude as they break the Sabbath. We know that Adam was commanded to keep the garden and to subdue the earth, he and his children. That was his job, but it was labor with a restfulness to it. The curse infused labor with hardship and futility. Just like God rested after 6 days of creation, the people of God are supposed to have rest after periods of activity.
The Sabbath is the historical inspiration for the modern weekend. However, it's interesting how the attitude towards rest days has changed in the time between Exodus and now. Many people were fighting for a two-day weekend earlier in the 20th century, while in the bible we read of people trying to cut corners so that they don't have to observe a "weekend" at all. On the other hand, modern electrical lighting allows people to work well past sunset, which would have been the traditional end of the day for so many generations past, so the possibility for working extremely long periods has greatly increased. Anyway, I don't think I have to write a social commentary here about overworked Americans, since nearly everybody else has already done that for me. Let's just say, ancient Israelites had the same problems, with the difference being that failing to keep the Sabbath is punishable by death. :) I guess things haven't changed that much after all.