Joshua led God's people after Moses died. Joshua brought the people into the land that God had promised to them. And he commanded their army in many battles against evil nations. God helped Joshua to win these battles. Joshua's first battle was the battle of Jericho (Joshua 6).
Joshua also directed the people to obey God's law (Joshua 5, Joshua 7 and Joshua 24). The Book of Joshua also contains records about the division of land (Joshua chapters 13-21).
The Book of Joshua is a history book from the Bible's Old Testament.