It is a common phrase usually meaning being at the extreme of a person's, or a piece of equipment's normal abilities/capabilities/knowledge and suggesting that to procede further would result in a state of being beyond the person's knowledge/abilities or a machine's capabilities.

Is it good to push past your limits?

Pushing past your limits means taking on newer, progressively harder challenges. If you're not challenging yourself to do bigger and better things on a regular basis, you're only working within the confines of what you already can do. That's a sure-fire way to stay exactly where you are and make little to no progress.

What does pushing your limits mean?

It means trying to do a little more than what's allowed, without suffering consequences. If you have kids, or if you've ever been a kid, you probably know what it means to push the limit. It means you know what's allowed, but you try to get a little bit more. When I was a teenager, I had a bedtime of about 10:00.