Hi ! Let's just quickly correct a small mistake: the right way to conjugate "correr" in the first person singular is "Yo corro." not "Yo corra". But having put that small mistake aside, here's the explanation:
If you say "Yo corro" it's the same thing as saying "I run" in English. It's the present tense, and it can mean that you're doing the activity while you say it, but usually it means that you do it with a certain regularity.
If you say "Yo estoy corriendo" it's the same as saying "I'm running" or "I am running". It usually means you're in the middle of doing something (like running) but it applies to any verb. For example "Estoy cocinando" means "I'm cooking". If you simply said "Yo cocino" it means "I cook" which usually means that you can cook, that you do it with a certain regularity.
Hope this helps. Buena suerte!