I learned in my German class that Gelb counts as yellow, gold and money. So why doesn't gold work??
I'm not a native so I can't say there is no such usage, but the most common usage is gelb = yellow, das Gold = gold, das Geld = money. They're pretty close to each other, but different nonetheless.
No harm in asking him/her what he/she meant. :) Do post it in here in case you find out about it.
I can barely hear the "l" in it. Can I completely skip it when pronouncing "gelb"?
No. The German "l" sound is different than most instances of "l" in English, however. It's made at the back of the tongue rather than the front.
From Proto-Germanic gelwaz, whence also derives Dutch geel and English yellow. Seems surprisingly different, but it was common for English to turn G's into Y's - for example: Garn (German) - yarn (English); Tag (German) - day (English). Anyway, that Proto-Germanic gelwaz derives from Proto-Indo-European ǵʰelh₃wós, which in turn derives from Proto-Indo-European ǵʰelh₃-.
Gold is a type of yellow, so personally, I think is should count if one enters yellow.