When people make mistakes or don't do the things they were supposed to, sometimes they try to give reasons why they didn't do it. For example:

Sorry I'm late. The traffic on the way in was crazy!

It's not fair. I wasn't given enough time to finish.

If you don't think the reason is good enough, you might say that this person is "making excuses".

If your children or employees make excuses to explain their mistakes, you can use this expression to tell them that you won't accept their reasons:

I don't want to hear any excuses. Just fix it!

I don't want to hear any excuses. You should have thought of that before you agreed to do it.

There's also a shorter version of this:

I don't want to hear it!