How does the ";"(semi-colon) affects the progress element?

Question

https://code.sololearn.com/WijdeaopF4dZ/?ref=app

Answer 1

https://www.sololearn.com/learn/HTML/2196/
Have you gone through this module?

You should not write semicolon on progress element.

Answer 2

I know that i shouldn't use semicolon with progress element but how do u define this