Three interesting things happen in Joshua 5 to move the people closer to their goal of being established in Canaan as the Lord's covenant people.
First, the men are circumcised. The generation that came out of Egypt had been circumcised. But over the ensuing 40 years, those born in the wilderness were not. Joshua rectified this problem in verse 3, then gave the men rest until they were healed (vs. 8).
Second, the manna stopped. What had been provided miraculously to the Israelites for 39 years to sustain them in the wilderness ended once the produce of Canaan was available to the people. When the promise was realized, the providence was no longer necessary (vs. 12).
Third, the Lord sends the commander of His army to assist Joshua in the military conquest of the Promised Land (vs. 13-15). It is time for the battles to begin.