Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means heaps, so the verb vocab version is to heap up. It can also mean to serve food, as in you're heaping on food onto someone's plate.
Please keep heaping up the food. I want more (もる), more, more.
Some Japanese people heap up salt on their doorsteps to drive away misfortune and evil spirits.