What does Joshua 2:1-21 mean?

And Joshua the son of Nun sent two men secretly from Shittim as spies, saying, “Go, view the land, especially Jericho.” And they went and came into the house of a prostitute whose name was Rahab and lodged there. And it was told to the king of Jericho, “Behold, men of Israel have come here tonight to search out the land.” Then the king of Jericho sent to Rahab, saying, “Bring out the men who have come to you, who entered your house, for they have come to search out all the land.” But the woman had taken the two men and hidden them. And she said, “True, the men came to me, but I did not know where they were from. And when the gate was about to be closed at dark, the men went out. I do not know where the men went. Pursue them quickly, for you will overtake them.” But she had brought them up to the roof and hid them with the stalks of flax that she had laid in order on the roof. So the men pursued after them on the way to the Jordan as far as the fords. And the gate was shut as soon as the pursuers had gone out. Before the men lay down, she came up to them on the roof and said to the men, “I know that the LORD has given you the land, and that the fear of you has fallen upon us, and that all the inhabitants of the land melt away before you. For we have heard how the LORD dried up the water of the Red Sea before you when you came out of Egypt, and what you did to the two kings of the Amorites who were beyond the Jordan, to Sihon and Og, whom you devoted to destruction. And as soon as we heard it, our hearts melted, and there was no spirit left in any man because of you, for the LORD your God, he is God in the heavens above and on the earth beneath. Now then, please swear to me by the LORD that, as I have dealt kindly with you, you also will deal kindly with my father’s house, and give me a sure sign that you will save alive my father and mother, my brothers and sisters, and all who belong to them, and deliver our lives from death.” And the men said to her, “Our life for yours even to death! If you do not tell this business of ours, then when the LORD gives us the land we will deal kindly and faithfully with you.” Then she let them down by a rope through the window, for her house was built into the city wall, so that she lived in the wall. And she said to them, “Go into the hills, or the pursuers will encounter you, and hide there three days until the pursuers have returned. Then afterward you may go your way.” The men said to her, “We will be guiltless with respect to this oath of yours that you have made us swear. Behold, when we come into the land, you shall tie this scarlet cord in the window through which you let us down, and you shall gather into your house your father and mother, your brothers, and all your father’s household. Then if anyone goes out of the doors of your house into the street, his blood shall be on his own head, and we shall be guiltless. But if a hand is laid on anyone who is with you in the house, his blood shall be on our head. But if you tell this business of ours, then we shall be guiltless with respect to your oath that you have made us swear.” And she said, “According to your words, so be it.” Then she sent them away, and they departed. And she tied the scarlet cord in the window.