What does Bij mean?

"Bij!" she texted right away when the date for the dinner was set.

Dutch student slang. This is a Dutch word. You will hear it a lot at Dutch universities, student associations and in student houses.

It is a pun. "Bij" means bee, but "erbij" also means being there. So in a group chat people react with a 🐝 to say they are coming. Everyone sees in one glance who joins. Also read about loca and OMW.