Interpreting cat interactions

We have 3 cats.

One cat, the youngest and most petite, is fairly food aggressive and always nudges the others out of their bowls during treat/churu time. That same little cat, went up to the oldest for a nose boop one day and the oldest backed off and kind of rejected her. She held her paw up to her face like some pimp about to slap someone or something.

She also sometimes puts her paw on his face.

What does that mean in cat language?