Here was i, the white man with his gun,standing in front of the unarmed native crowd seemingly the leading actor of the piece; but in reality I was only an absurd puppet pushed to and fro by the will of those yellow faces behind . Please line explanation

The power dynamic of the colonizer-colonized is reversed in this instance as Orwell feels himself, not a puppet of the Empire, so much as a puppet of the crowd. It’s them for whom he must perform. In that way, they are the ones with power. This is what he means when he speaks of the “hollowness” and “futility” of his presence in the east.