Meaning
A person kneeling, resting on one or both knees, usually shown facing left. This is the gender-neutral version; man and woman versions exist, as well as facing-right variants, and all come in several skin tones.
It is used for pleading, apologising, praying and the dramatic gesture of begging a friend for a favour. It also shows deep respect or admiration in a joking way: โPlease lend me your notes, I am literally on my knees ๐งโ