Well, I'm just going to think out loud. Material is exactly level. The pawn on b7 is under attack. I check all possible checks and captures - nothing significant there, so b7 will have to be dealt with in some way. The pin on f3 is awkward for White, for example, if he breaks it by Be2 then his e2 bishop and e1 rook are less active; then Black shifts diagonals to ...Bg6, annoying the rook on b1. White has a slight advantage in development (bishop is at home, but both rooks are on good files), and an advantage in space. White has 3 pawn islands to 2, but no glaring weaknesses. White will want to develop the c1 bishop, deal with the f3 pin, and work toward pushing his c and d pawns. If Black can play ...h6 soon then the c1 bishop might not have a strong square. d5 and c4 may be good posts for the Black knight.

Okay, candidate moves include 1...Qc7, 1...b6, 1...b5, 1...Rb8. I hate to waste a rook on defending b7, unless I think pushing the b-pawn is good, or I can open the file. Neither seems to apply. 1...Qc7 doesn't seem very strong, but maybe playable. For 1...b6 to make sense I should want to follow up with ...c5, but that doesn't feel right. I would rather play 1...b5 (slightly anti-positional, but c6 is not really vulnerable). The follow-up could be something like 2.Be2 Bg6, which looks good for Black (reasons noted last paragraph), or 2.Bd3 Nb6 3.Be4 Bg6 4.Bxg6 hxg6. In this case both of Black's minor pieces are a bit better, and White pawn front is fixed. I don't see any kind of knockout blow.