The adverb BENE is used to describe how an action takes place, in particular, it is used to indicate we can satisfactorily do that action, namely in a proper, correct way.
Example:
“Parlo bene italiano” (I speak Italian well)
“Suono la chitarra abbastanza bene” (I play the guitar quite well)
The opposite of the adverb “bene” is "male".
Example:
“Io parlo francese molto male” (I speak French very badly)