In this game, you'll have to complete missions while managing the growth of your trees and animals, keeping them healthy and well fed so you'll later have good produce to sell.
It'll be a while before you see any real results, so you have to manage the money you spend in the beginning well, choosing what to spend it on carefully. If you harvest too much of something, it'll spoil and you'll lose it.
On the other hand, neighbors will come to your farm every day looking for their favorite produce, so you should always have extra stock ready or be ready to go out and collect it for them. The faster and better your service, the greater profits you can get and the better-oiled your produce machines will be on your Let's Farm.