What is f stop on a camera? How do I change it?

I am pretty sure it has to do with the focus, if that helps at all. The front of the lens should let you turn it to adjust your focal point, f-Stop might mean it is on autofocus? I don't know about your camera, but my lens has a switch to turn off my autofocus. Note that I am still new to this, I just wanted to add something.