Meaning Be back later
Type Acronym
Rank ★ ★ ★  Common
Usage Online Only (chat, messaging, e-mail)

BBL means be back later. It is used to communicate that sender will be back sometime, but not necessarily right away.

BBL is similar to the BRB, BBIAB, and BBS acronyms, which are all used to tell a person that you aren't available at the moment but will be back again. The acronym is commonly used when texting or in online chat when you have to run an errand or attend to another matter but plan to be back to chat later.

Updated August 24, 2016
Information from PC.net