What does "buying more house than you can afford" mean? Why shouldn't you do this?

Basically it just means that you are trying to spend money that you don't have on things you don't need.

Step-by-step explanation:

Taken literally, you can live in a pretty small house and be content. You don;t need to spend tons of money to be happy. This can be a bad thing to do because you don't want to be in debt to anyone, especially when that could have been avoided.