If you’ll excuse me,...what?
In movies and drama series, I have seen a character says "If you’ll excuse me," and just takes off.
What exactly does this mean? I can guess a vague meaning from the context, but I'm not sure how to use it.
I assume you don't really need to say anything after "If you’ll excuse me," and everything is understood.

Question

If you’ll excuse me,...what?
In movies and drama series, I have seen a character says "If you’ll excuse me,"  and just takes off. 
What exactly does this mean? I can guess a vague meaning from the context, but I'm not sure how to use it. 
I assume you don't really need to say anything after "If you’ll excuse me," and everything is understood.

Answer

It means, “I can no longer participate in this conversation or situation,  I must go, now”.

Answer

Yes, it is a shortened, polite form of, "If you'll excuse me, I'll take my leave now."  Meaning that they are going to leave.  It is a way of avoiding a long explanation, especially if you are in a hurry.

Answer

It's short for "If you’ll excuse me, I'll leave now."

Answer

In TV shows this is meant to be a funny or dramatic way to leave - when someone says these words they're going to leave no matter what, but it sounds more polite (and often more dramatic/funny) than just directly saying "I'm leaving!"