"To tread the boards" is to be a theatre actor... the boards being the stage floor. "Trod" is just the past tense of "tread", so this means the person was an actor in the past.

As Kat said, it's a slang expression meaning that someone is an actor.

Tell me, please, which means "Trod the boards"--> Tell me, please, what does "trod the boards" mean? One meaning of the verb tread (tread, trod, trodden) is "to walk over." So, "trod the boards" literally means to "walk over the boards." According to THE NEW PENGUIN DICTIONARY OF THE THEATRE, boards are "The constituent parts of a stage floor, variously supported by vertical posts, tie-bars, or bracing. Hence the phrase 'tread the boards', meaning acting in general" (p. 74). An old-fashioned way for an actor to say good-bye to a fellow actor after a production run is to say, "Till next we trod the boards." But I've never actually heard anyone say this.

"Trod the boards" literally means to having been (past tense) on stage. Thus it's most usual meaning is a reference to stage acting. However, rock musicians play on stages and in theatres as well, and I have heard and used the term to refer to being onstage as a rock musician as well.