Schmaltz is term for "fat" in Yiddish. You can apply it to anything though. So if you say something has too much schmaltz, or is schmaltzy, it basically means blubbery, or wordy, or melodramatic, overdone, too much information, or plain full of baloney.
Michael R sums it up very well, it's like malarkey.
If you can't find the answer in APUG then it probably is a really dumb question.