That's the pronunciation you heard, but that's not how you spell the word. He says a "decent" cup of coffee. It means satisfactory, acceptable, tasty.

I recommend that you look up the words "decent" and "descent" in a dictionary like Oxford or Collins, and listen to the audios. If you listen carefully, you should hear these differences: a) main stress is on "de" in "decent", and "scent" in descent" b) first vowel sound in "decent" is long /iː/; first vowel sound in "descent" is short /ɪ/ c) second vowel sound in "decent" is schwa /ə/; second vowel sound in "descent" is /e/