When someone uses the single letter "b" in a text, it usually means the word "be." Granted, definitions for letters and symbols that are used as shorthand can vary among mobile users, everyone understands "be" to unequivocally mean "be."
In text messaging, the letter "b" isn't always used alone; texters frequently pair it with other letters to give it new meaning. It's arguably most seen as "bff," for "best friends forever." Another popular abbreviation is "b/c," slash optional, for "because." There's also the ever-popular "btw," for "by the way." Lesser-known abbreviations include "btaim," for "be that as it may," and "byom," for "bring your own Mac."
