盖(gài) - to cover, to build, lid in Mandarin

盖 (gài) is what you do when you put one thing on top of another to hide or protect it: a blanket over a child, a lid on a pot, snow over a yard. As a noun it is the lid or cover itself, usually said as 盖子.

Two extra senses are worth learning early because they come up constantly. 盖房子 is to build a house, so the verb covers construction as well as covering. And 盖章 is to stamp a document with a seal, which in Chinese officialdom matters far more than a signature does.

The trap for an English speaker is that 盖 rarely stands alone as a finished action. English says "she covered it" and stops; Chinese usually wants a complement, so 盖住 (covered it over), 盖上 (put the cover on) or 盖好 (covered it properly). A bare 盖 in that slot sounds like the sentence was cut off.