Is trade-offs the fact that we cannot have everything we want

This is true.

Trade-offs are based around the idea that in order to get something, we have to sacrifice something in return. A simple example would be you going to work. You earn money but you sacrifice your time in order to do it. In order for one thing to increase, another thing has to decrease in a trade-off, which means that you can't have your cake and eat it too.