Having confidence in yourself means that you believe in yourself. You know that you can do anything you put your mind to. For example let's say you want to go to the college of your dreams but it's not necessarily the easiest to get into. You have confidence in yourself if you believe you can make it into this college that you dream of. It might be hard but you think that you can do it in fact you know you can because you have so much faith in yourself.
Of course, it’s always possible to have too much confidence that then becomes arrogance. You become full of yourself and might bring others down along with your success. Let's say you wanted to. All you talk about is yourself and how you can do every little thing out there even if it’s impossible. That becomes a burden to others and you’ll end up looking stupid if you try to do something and fail when you said that you could do it no matter what.There was a time when I was confident too. In fact I needed to be confident to get an extra little boost for my games. I played soccer every weekend and i'm not going to lie, I was pretty good. That was mostly because I always had confidence that I could score a goal or that I could give a good pass to my teammate and that always helped. I started to believe that I could achieve anything I wanted therefore I put all my effort into doing all I could on the field. That caused me to become a better player and I spread this confidence with the rest of my team and we all did great together.