Isaiah continues to describe the time when God will save the people of Israel. Although these events will happen in the future ([Isaiah 9:1](../09/01.md)), Isaiah describes them as if they have already happened. This emphasizes that they certainly will happen. (See: [[rc://en/ta/man/jit/figs-pastforfuture]])
The word "you" refers to Yahweh. The word "their" refers to the people of Israel, but Isaiah includes himself as part of Israel. Alternate translation: "Lord, you will greatly increase our people and our joy" (See: [[rc://en/ta/man/jit/figs-you]])
The joy that Yahweh will give Israel is described as the same kind of joy people have when they bring in a harvest or divide valuable plunder. Alternate translation: "They will rejoice before you as people rejoice when they gather their crops or when a battle is over and soldiers divide what they took" (See: [[rc://en/ta/man/jit/figs-simile]])