This position is almost certainly a draw. Black's next move could be Ba8, blocking the a7 pawn and putting the bishop out of harm's way. So how would White proceed from there?
One possible White plan is to promote the a7 pawn. But the promotion square is light-colored, so it cannot be supported by the White bishop. To get support from the king, White needs to get their king to c7 and then b8. (b7 and c6 are guarded by the Black bishop, so the White king cannot use those squares.) But how? If they move the c7 bishop and then play Kb6, Black simply plays Kd7 (or possibly Kd6 or Kd8 if they need to waste a move, depending on the position of White's bishop.)
Another possible White plan is to take the g4 pawn. It's on a light square, so it cannot be taken by the bishop, so that means the king has to do it. But that doesn't work either. White's's king would need to get to f4 (perhaps via e3), but Black can easily move their own king to f5 (or e5 or g5) in time to prevent this.
I don't see any other possible plans. The Black bishop cannot be captured (we've established that the White king cannot get to b8 to threaten it) and the e4 pawn is protected by the Black bishop. Since the White king cannot penetrate into Black's position, the pawns are blocked, and the White bishop cannot make progress on its own, the game is drawn.
[FEN "8/P1B5/4k3/2Kb4/4p1p1/6P1/4P3/8 b - - 0 1"]
1... Ba8 2. Kb6 Kd7 3. Be5 Kd8 4. Bb2 Kd7 5. Kc5 Ke6 6. Kd4 Kf5 7. Ke3 Kg5 8. Kd4 Kf5 9. Kc5 Ke6 10. Kb6 Kd7