What do corporate counsel do?

Counsel - are they people who help companies to deal with legal issues? Is 'counsel ' a plural word, meaning 'many advocates' ? Sorry , i'm not a native speaker

To "counsel" someone means to advise them. A "counselors" provides advice (of various types).

In US companies, lawyers are sometimes refered to as "counsel" since they provide advice that can determine the best course of action or define the legal options available for a situation.

The title "General Counsel" (or GC) is a common title for a senior lawyer employed by a company to look after the company's legal affairs.