Is it ok to hide mistakes? So, every time I admit I made a mistake, my grandfather (when he's there) tells me that I shouldn't admit my mistakes. Is that ok? Should I admit I made a mistake? I have no idea what to do!

I believe you should accept your mistakes and learn form them.

Yes, as long as it doesn't hurt anyone's feelings. For example: don't say something along the lines of "hey, I lost the save file on your favorite game", or "I was the one to eat the last cookie." However, do mention important stuff like, "I'm missing a lot of assignments in school", or "I've been doing self harm." See the difference?

It's ok to admit mistakes

Yep

Well,it depends.For me,if I make a mistake than I try to fix it by myself.If I can't I'll find help,but I'm usually able to do it myself.As long as you learn from your mistake and don't make it again I think it's okay not to admit it,but this just my opinion.

You should admit your mistakes. No one is perfect, we all make them.. There is nothing wrong with it.