In this chapter, Joshua sends two spies into Jericho who are secretly aided by Rahab, a resident of Jericho.
This is the second time the Israelites have sent spies into the promised land. The first time was in Num 13 and ended very poorly. The spies gave a bad report, the people rebelled, and they were condemned to wander in this wilderness for 40 years until the whole generation had died. This chapter parallels that earlier chapter to an extent, but there is a notable difference. Instead of sending 12 spies (one from each tribe), in this chapter the Israelites only send two spies without stating their tribal affiliation. What this tells me is that this story is less symbolic and more practical. In Num 13, sending a spy from each tribe is a symbolic gesture of equality between the tribes and also symbolizes their invasion (which was subsequently delayed). Here in Joshua 2, Joshua is a far more practical leader, since he sends fewer spies (who are thereby less likely to be caught) and Joshua also emphasizes gathering military intelligence related to the invasion ("especially Jericho", v. 1). To be fair, Num 13 was also gathering military intelligence about the size of fortifications and available resources in the land (needed to sustain an invading army).
Anyway, it seems like the main character in this story is Rahab, who first hides the spies, then lies to her own people, and then advises the spies on how to evade their hunters. Rahab is also the only named individual in this chapter: the spies, the king of Jericho and the various other figures are all anonymous, except for Rahab. In short, Rahab made a deal with the spies to save their lives if they agree to spare Rahab and her family when the Israelites destroy the city. This chapter also explains her reasoning, when she says that she, and all the people of the land, are terrified of the Israelites because of the stories they heard about the plagues in Egypt and the crossing of the Red Sea.
I don't think Rahab is very significant in terms of the story here, because this part is just one chapter and it is relatively insignificant compared to the rest of the events in Joshua and the following books. However, I do think Rahab is somewhat significant because of how she is referenced in later places in the bible. Perhaps most significantly, Matthew 1:5 specifically names Rahab as the mother of Boaz, who is the great grandfather of King David. There isn't any textual references to this here in Joshua or later in the book of Ruth when it discusses the genealogy of King David there (cf. Ruth 4:18-22). James and Hebrews also refer to Rahab as an example of faith, claiming that it was not fear but rather faith in the LORD that drove her to assist the spies (James 2:25 and Heb 11:31). So it is clear that the NT draws upon Rahab as an example of faith and possibly someone who helped bring Jesus into the world. In the OT references to her are sparse; she is only mentioned here and later in Joshua 6 when Joshua fulfills the promise to spare her.
How is Rahab an example of faith? I think this is mostly because of her claim in v. 11 when she says that the LORD is the one true God. More significant in my opinion is the fact that she's a woman from a foreign nation, even one of the nations that the Israelites are supposed to wipe out. If you recall from reading the Pentateuch, Israel is supposed to be a nation that is open for everyone to join. The covenant of circumcision is available for every man who wishes to eat the Passover, and for women the process is roughly comparable. In the OT however, this rarely happened. There are only a handful of converts mentioned in the OT, and they are generally regarded very favorably. One example we have seen is Caleb (Num 32:12 calls him a Kenizzite) and Rahab is another. There is also (in the book of Ruth) Ruth, who is a Moabite. These are all significant figures in the OT, but it's still clear from the rest of the text that a major prejudice against the Canaanite tribes existed in Israel. And why not, considering the Israelites were commanded to kill them all? But Rahab and Ruth both join Israel regardless and they are honored in the bible for it.
In the end, the two spies return to Joshua and tell him that the inhabitants are in fear of them. So it's like a reversal of what happened last time when the Israelites melted in fear of the Canaanites. Now the Canaanites are melting in fear of the Israelites.
One last minor note. Since we know it took the spies at least 3 days to return to Israel and Joshua said the people would depart in 3 days, that must mean that the spies were sent out immediately and the Israelites left to cross the Jordan very shortly after the spies returned.