"Your students look a likely bunch" More context is needed to know exactly, but "likely" is being used as an adjective. I would assume that it means "suitable" or "promising" (= could be good/useful).

More context is needed to understand the statement. As it is right now, I would be looking for a prepositional phrase to explain the statement. For example, "Your students look like a likely bunch of volunteers." Here likely is saying that I think your students might make good volunteers for the project I need volunteers for.

Try to rewrite right sentence