'Es' in Spanish means '(he/she/it) is.' It's an irregular verb form of ser, 'to be'. For example: El gato mio es simpatico (My cat is nice.) In German, "es" is the indefinite pronoun for neuter...
Percocet (a trade name of Endo Pharmaceuticals for a narcotic pain killer containing oxycodone and acetaminophe) is an analgesic, the ES refers to the Extra Strength formulation.