What does it mean if the moon is waxing and waning

Both verbs come from Olde English.

That's why everybody clearly understood their meaning until

a hundred years ago, but nobody understands them now.

"Waxing" = growing

For two weeks after the New Moon, it's growing toward Full.

First it's a waxing crescent for a week, then it's waxing gibbous.

"Waning" = shrinking

For two weeks after the Full Moon, it's shrinking toward New.

First it's waning gibbous for a week, then it's a waning crescent.