Im 13 year old boy and i just had surgery.....?

im in the hospital now because i had knee surgery and the doctors got me on nose oxygen thing but 10 min ago i overheard doctors in my room saying that they are putting me on a foley catheter in a little bit. I don't know what that is, and explain what they do with it, how they get it on me, does it hurt, should i be scared.......PLEASE HELP