In Mexico, it usually means "Yes" but in some cases is more like a "Im listening" . Even though all Mexicans understand this expression. It is more used in the northern part of Mexico. Used in US as well
"-¿Te vas a comer eso? -ei. -Are you going to eat that? -ei"
* Only one "like" per meaning and day, the more "likes" the meaning will appear higher in the list