1.Nf3 Nf6 2.b3 d5 3.Bb2 Bg4?
Black development plan is very simple, the main line goes like this:
1. Nf3 Nf6 2. b3 d5 3. Bb2 Bg4 4. e3 Nbd7
5. Be2 e6 6. O-O Bd6 7. c4 c6 8. d4 O-O 9. Nbd2
In this position, despite white bishop aiming it is own pawn it is still potentially dangerous; therefore, standard
c5 breaks are not usual in this position.
The safest approach for black is try to exchange the dark-squared bishops with
9...Qe7 10. Ne5 Ba3.
Another approach, most intuitive in my opinion, is
9...Ne4 10. Nxe4 dxe4 If white plays
11. Nd2 then after
11. Bxe2 Qxe2. 12...f5 black has play on the king side, the bishop is aiming at h2 and the queen can be brought to
h4 or/and rook to
f6. If white plays
11. Ne5 and then
11... Bxe2 12.Qxe2 black could play
13. Nxd7 and here again black can play on the king's side.
It is also common to bring the queen play
9...Qb8 with the aim of controlling the
e5 square and preventing
Ne5. But I am not very familiar with this plan.
Also, the position you describe can be reached via
1.Nf3 Nf6 2.g3 move order.
1. Nf3 Nf6 2. g3 d5 3. Bg2 e6 4. O-O Be7
5. b3 O-O 6. Bb2 c5 7. c4
to avoid it you can go for the same black setup, with the bishop on g4.