If you just want to stop the hole from expanding, I'd sew a circle around it and slightly pull it together. If the hole is too big and the pulling resulted in wrinkles, I'd do 4-8 diagonal connections on the inside of the cloth (so the hole looks like a cut pizza) and then sew a spiral until you reach the middle of the circle.
If you want to turn the hole into a little art project, you can also look up 'visible mending' on the search engine of your choice.

