The idiom to keep something from somebody means to prevent someone from doing something or to keep something a secret from somebody.

1. You must have known that I would find out the truth eventually, so I don't know why you tried to keep it from me.
2. I tried to keep him from gambling his money but he did it anyway.

1. It doesn't matter how bad the news is, you should not be keeping anything from me. If I am to turn this business around, I need to have all the facts to hand.
2. I didn't want the interviewers to know that I had been fired from my previous job for misconduct, so I kept that information from them.