"Ya dancer" or "Ya wee dancer" is of Scottish origin. This expression means - Excellent! Great! Fantastic! Etc etc etc. For a reference, you can check the film Trainspotting where Sickboy uses the expression perfectly.
A brilliant, earth-shattering word that Mary J. Blige invented to accentuate the rhyme-scheme of a masterful song, placing her among the accolades as the Shakespeare of our age.