The book of Joshua kicks off the section of Old Testament history in the modern Christian Bible. It’s also the first book of the Former Prophets in the Tanakh, the Bible of Jesus’ time. The Old Testament is largely about how the people of Israel came to their land (and lost it), and Joshua begins Act One with the people of Israel entering the promised land of Canaan and then facing a choice: will they remain loyal to the God who gave the land to them, or will they turn from him and try to keep the land themselves?
NOTE: LOL somehow despite all my planning, I wrote "east" and "west" on the WRONG SIDES of the Jordan River. In reality, most tribes settle WEST of the Jordan, and a few stay EAST. I'm a real goofster sometimes.
You can read a more indepth summary of the book of Joshua here: https://overviewbible.com/joshua/
You can learn how Joshua fits into the Bible as a whole in by book, The Beginner's Guide to the Bible: https://overviewbible.com/product/beg...
And if you want to do this kind of Bible study yourself, check out Logos Bible Software: https://overviewbible.com/logosbible...