Meaning of "about" in Essential American English Dictionary

about

preposition us /əˈbɑʊt/

A1 relating to a particular subject:

What was she talking about?
what/how about…?

A2 used to suggest something:

What about some lunch?
what/how about…?

B1 used to ask for someone’s opinion on a particular subject:

How about this restaurant? Is it good?

(Definition of “about preposition” from the Webster's Essential Mini Dictionary © Cambridge University Press)