Here's the ELI5 explanation (not 100% accurate but pretty close)

Elementary school: years 1-5

Middle school: years 6-8

High school: years 9-12

Bachelor's degree: years 13-16

Master's degree (graduate degree because you've graduated from college): years 17-18

Doctor of Philosophy (PhD) (also graduate degree): years 17-20

Once you're in college schedules get flexible so those times are approximate. There is also post-doctorate study. Because graduate work is entirely subject-specific it's possible for people to get multiple master's or PhD degrees. Medical practice requires on-the-job training after you get your M.D. degree, roughly years 21-22. Psychiatry also requires additional training after your M.D.

Something to look forward to!