This position shows the importance of the Kings being centralized in the endgame. Black needs to keep in mind something that you'll learn if and when we learn King and Pawn endgames, the Rule of the Square (you can check out YouTube, I'm sure there are examples there). Basically, this rule says that the opposing King (let's say, as here, K on B2) needs to be within the square created by the current position of the Pawn and the Queening square.
Look at my enclosed diagram (Example 2) to clarify.
Black's King on b6 is in the yellow square (square goes both left and right, so it is in the square - just showing right so I can show White's as well in same diagram). White's King is in the red square. Because each King is in the square, they can get to the Queening square (c8 and a1 respectively) before the pawn. If they are outside the square, they will never be able to catch the pawn from Queening.
So if Black's King is on the h-file (illustrated here by a King on h6) or on ranks 1-3, he would never be able to stop the pawn at b8. Conversely, if White's King is on even the e-file (King on e3 here) or ranks 5-8, he will not be able to stop the pawn. This assumes it is the opposing player's turn. Try it. Move the pawn and King outside of the respective square, with the opponent pawn moving first, and you will see that neither King can capture the pawn before it Queens, and cannot take it when it Queens. In both examples, if the King can get inside the square, before it is the opponent's pawn turn to move, he can capture the pawn on the Queening square. Try it. This is the Rule of the Square. This is Endgame 101.
So if the Kings were the right side set of Kings (h6 and e3 Kings), then Black would win, because he would queen first regardless of whose turn it is (The pawn on a4 is also an Advanced Pawn, so will reach the Queening square first). The Outside Passed Pawn would also be an advantage in this kind of position as well. It should be a countable Point (or two for the Advanced Pawn) for Black in either scenario.
This is a great example of Advanced Pawns, Outside Passed Pawns, having the Kings centralized in the endgame, and the Rule of the Square, all in one place.