Moses says what the army officers must say to the people of Israel before a battle. In ancient Israel, men were excused from fighting in battle for several different reasons. Some of these reasons are mentioned in this chapter. Apparently, needing to establish a new house, the need to harvest a field and cowardice were possible excuses.
"If any soldier here has built a new house and has not dedicated it, he should go back to his house". The questions are intended to tell the readers that Yahweh only wants soldiers who are completely dedicated to fighting for him.