A man volleying a football

It means kicking the ball while its in the air - in front of you or to the side of you.

When your opponent is at the net volleying the ball and you hit a winner past them where they cannot reach.

There is no adverb form. The verb has the participle adjectives volleying and volleyed, but neither has an adverb form.

Willam Morgan a P.E. director at Y.M.C.A. in 1895 was demonstrating the game when a spectator said it included a lot of "volleying" therefore it was renamed Volleyball