On Instagram, "su" typically stands for "shoutout." It is often used when users promote someone else's account by recommending them to their followers. This can be part of a shoutout-for-shoutout (S4S) arrangement, where two users agree to share each other's profiles to gain more visibility and followers.
SU means WITH
His as of his pants '' su pantalon''
Su autorización - Its okay
Su hyun
It can mean "your" (formal) or his, or her.
"Su casa" means "your house."
"Su amigo Pedro" means "his/her friend, Pedro"
"Su hermana" means "his/her sister" in English.
"Su mano derecho" means "his/her/your right hand."
Estoy a su bebe in English means I am a baby.
"Su hermano" in Spanish means "his brother" or "her brother," depending on the context in which it is used.
While some people refers it to InstaGram. The most common acronym for InStaGram is "Insta" or "ISG".