They're, like, some words you uh... you throw them in when you don't know what to say. Used in the middle of sentences when... um... you're trying to think of a point. Common examples are "uh," "um," and "like." Overuse of them can, like, totally ruin the tone of sentences and make you look weird.
So, uh... this is the part where I, like, put a sentence that uses fillerwords... um... I can't really think of anything.
The little two-word chat that you initiate with someone while waiting for other interesting people to reply (or a video to finish loading) and which you don't bother going back to as soon as the interesting windows start showing some action - Usually caused by restless scrolling through one's contact list during the wait
Marc: Wassup?
Jenny: Hey where have ya been?! I had SO much to tell ya!
*Long Gap with no reply*
Jenny: Did you just filler chat me?!
Gas Station Pumper: Ay, buddy, what you like?
Driver: Stuff it up your turban, bitch!
Gas Station Pumper: Huh? I can't hear you.
Driver: I said, "Filler up!!"
{noun} Someone who is present in a situation as filler, i.e. the commercial in between the main event or the opening band no one knows or cares about.
"God damn, I'm not going to be the fillerbitch in this season." - Any reality TV star, really. (See also: Adore Delano of RPDR, who is loosely quoted here.)