She drives badly. - Badly describes how *she* drives. Her driving is bad. - Bad describes her *driving*.

Hello! "She drives badly" is correct because it is an adverb that tells us clearly about how she is driving - not well at all. I hope that helps!

She drives badly. You use "badly" because it is an adverb (a word describing an action). He walks quickly, the children play quietly etc.

Badly. It is an adverb. I think "she drives poorly" would be better.