Hi, Letajah
There is no age requirement for publication (bear in mind we are agents, not publishers). We look for a standout concept and mature writing, whatever your age. However, the publishing industry requires a mature approach –  authors who are able to deal with ups and downs, and the demands of dealing professionally with the deadlines and requirements of  publishing contracts. This generally suggests a writer who is at least in their late teens, but of course there can occasionally be exceptions to that. 
 
Good luck!
Sarah