Waxing Gibbous Moon emoji is the picture of one of the phases that the Earth 🛰️ Satellite comes through the month — the fourth one in order. It is basically something opposites to the phase represented by Waxing 🌙 Crescent Moon emoji — i.e. the biggest part of the moon is lit, while there is still a thin dark crescent on the left side. Many people use it in relation to magic, hope, mysteries — probably because it resembles the 🌕 Full Moon.
Examples of using
“Being lonely at night hurts 🌔”
“Good days are about to come 🌔”