The unconscious transfer of one’s own desires, emotions or personality traits on to another person.
If you want to know who someone truly is, look at what they accuse everyone else of doing. Also known as the “Thieve’s curse”. A thief is afraid of everyone stealing what they own, because they steal from everyone. Likewise… a Liar… accuses everyone else of being a liar. Because they assume everyone else is just like them.
Likewise, unsolicited advice is typically advice the person giving it needs to hear themselves.