I presume you’re referring to the Italian-American word capisce. To my astonishment, Urban Dictionary’s entry is not half bad:
Capisce (pronounced cah-PEESH) is an Italian word that is used in American slang to say “got it” or “understand.” The correct word in Italian would be capisci (pronounced cah-PEE-shee) to address the second person informally, a.k.a. you.
(I’m presuming the dropping of the final vowel is Italian dialect.)