Bay Area slang for, "You know what I mean?"
Popularized by the hyphy movement, but in my opinion, comes originally from thick spanish accents. I had a landlord in San Jose who would say it constantly and I don't think he was into hyphy...
"Yada" in hebrew means "know". Yadadamean is a bay area slang meaning "know what i mean". The bay has many people who subscribe to the "black hebrew Israelite" theology.