What does having a blackbelt mean?

[chinto]

I was thinking about this when I was watching some blackbelts on youtube. Does it mean you can fight? Does it mean you simply know all the content in your system? I have seen my fair share of blackbelts that have good form and can throw a kick but as soon as a punch is thrown they are closing their eyes and looking away.

SO what does a blackbelt mean exactly?

that you understand the very basics and are ready to go back and start again and learn more.