Yes, EXCELLENCIES is a Scrabble word!

Letter values in Scrabble US: E 1, X 8, C 3, E 1, L 1, L 1, E 1, N 1, C 3, I 1, E 1, S 1.

Is it a valid word?

EXCELLENCIES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a title used to address dignitaries (such as ambassadors or governors); usually preceded by `Your' or `His' or `Her'
an outstanding feature; something in which something or someone excels