A loanword of Italian origin, capisce is the third person form of the word capire, which means "to understand". It is usually placed at the end of a bit of dialogue, an order, or anything that may be hard to follow. The "Do you understand?" implicit in this word's placement can also refer not to factual understanding, but a question as to whether the person being spoken to will agree to the conditions just laid out as they stand. Sometimes, it is not a request for acquiescence, but an order.
Examples:
Do you understand the instructions?
"The drill bit goes in this socket. Now, it can be hard to remove, so don't go crazy trying to get it out. You'll break the whole F*ckin' thing trying to get the bit out, capisce? Damn college kids don't know a damn thing about finesse."
Will you acquiesce to the conditions?
"Your sister is going to get the
packing plant, and I don't want to hear another goddamn thing about it. You got a
coke problem that costs me, son. And I don't want to cut you off, but you leave me no choice. (Pause, followed by a coughing fit.) You gotta promise not to make trouble for her, capisce? (Two coughs this time, hard) It's not her fault you're such a
putz."
This is what will happen, regardless of your agreement:
"The money, Frank, the money. You keep going on and on about your sick mother, and your new mortgage. These things do not concern me. What concerns me is that I have the money in a week. You got a week to iron out your finances. No more extensions, which I have been kind en- (Frank breaks in, questioning the kindness of an extension with a 25% interest hike attached to it. This is a bad idea.) Okay, you know what I will do for you Frank? I will give you a guarantee. I guarantee that if you don't get me my money by next Thursday, some men are going to visit your pretty little wife. (Frank starts to become emotional.) If the money isn't here in my hand, I can't help you, capisce?"