Surfing Waves

What board should I use? What is the difference?I will be turning 14 in 14 days. And on my birthday I am going to go surfing for the first time, my uncle was planning this for a long time. I am 5 foot 5 inches. I weigh 120 lbs. I know the basics. I got upper body strenght

Congratulations on your up coming birthday, I wouldn't sweat it too much if your uncle has had this planned for a long time he probably even has an idea of a board for you. At 14 I would consider a board with a bit of length but you wouldn't have to go to a long board .I wouldn't go ridiculously short either! Good flotation will make paddling easier and that means catching waves easier.
Lots to learn about how much there is to learn enjoy thoroughly