You realize her palm or wrist would be on her labia and clitoris, which is where your fingers go when you "finger yourself". Clearly she's covering up her delicates with her hands because she's nude so as not to reveal anything; but it's not like I'd expect you to grasp such a simple concept though.
She is holding the panties with her
ring finger and pinky finger. Her middle finger and pointer finger still could bend enough for her to finger herself.
And she's rubbing her nipples, or you could say she is covering them but of course you would say that for lolicron.