What is the meaning of ב־?

in

at

with

In (a place or time).

With

1. By means of, using

   By means of, using

   In a manner characterized by

   While, during.

   While, during.

   Among.

   On (a medium of communication).

   To the power of: Indicating an exponent.

   The forms בָּם and בָּן are archaic except in poetic use.

   Source: wiktionary.org