My son made a small hole in the pool side with a weed wacker what should you do?

I assume you have an above-ground pool by your question. Regardless, water physics dictates that you make any repairs from the inside of a leaking vessel (that is the water-side, it would be the outside if a boat). The water pressure is greater than the pressure of the air outside, so, any patch on the outside would eventually (sooner than later) leak. There are a variety of vinyl patch kits available, but none that work under water, so you would have to drain it first, and then follow the patch kit instructions. The EASIEST way to patch this would be with a product called "Mr Sticky". You can get it at most pool supply houses, or, if not near one, you can order online. It is an underwater epoxy that is extremely easy to use, even for a novice. Follow the mixing instructions (squirt it onto a piece of cardboard, mix it together and spread it over your hole with a popsicle stick!), and apply. The great thing about this stuff is you can use it underwater. Very cool. Good Luck!