The speaker is somewhere unfamiliar, surrounded by waves, animals, and traffic on a highway but no one to talk to. The sounds of the place are the only company they have, and the people around them are strangers. Then the poem turns inward: the speaker wonders if they are a stranger to themselves too.
The word "invincible" keeps coming back, and it doesn't sound like a boast. It seems to mean untouchable, cut off from everyone, and maybe hiding. The speaker admits they would keep quiet even if someone were there, because they're afraid to say how they really feel about themselves. The ending is the most telling part. They believe everything that goes wrong is their fault, and they decide that if the world sees them as invincible, they must be. It reads like someone borrowing a tough image to cover pain. The mood is lonely, quiet, and quietly heavy.