What does it mean to take a second mortgage out on a house

Taking out another "mortgage" on your current house so that you will have 2 house payments instead of one.
It can be done for various reasons and not always a bad thing and rarely a great thing.

Just that, you are borrowing on the equity you have on your home. You owe both lenders (or the same one) for both loans.

[big]if you can don't take one it's more debt t pay

It means you’re borrowing more money and using your home’s equity as collateral. You’ll have another monthly mortgage payment along with the original..

It means you need more money

You get f***ed twice.