Plath uses an extended metaphor, that of a cadaver wrapped in burial cloth, to create an image of her outer covering, her skin, as her perceived identity. Lazarus was a man pronounced dead whom Jesus reportedly brought back to life, though he had already lain for four days dressed in his burial shroud. Plath compares herself to this, creating images of her skin being "peeled" off or "unwrapped" as allusions to this story from the New Testament. In this poem, her skin becomes the layers of cloth that create the shroud.
She describes her skin as a "lampshade" and "linen" and says:
Peel off the napkin
O my enemy.
Do I terrify? --
This images conjures up the sort of suspense from a horror movie like The Mummy, in which one wonders, "What's under all those bandages, anyway?"
She goes on with the metaphor of "unwrapping:"
The peanut-crunching crowd
Shoves in to see
Them unwrap me hand and foot --
The big strip tease.
These are my hands
Here, she creates the idea that the resurrected body is part of a sideshow or carnival, and people have paid to see the "freak" be unwrapped and revealed.
So, Plath, using the metaphor of a burial shroud, reminiscent of the Biblical reviving of Lazarus, creates an image of her identity as being connected to the external, the skin-deep. This is contrasted with the horror to be found when this identity is unwrapped to reveal the "real" identity beneath.
I edited out the second question that you asked about relating the poem to themes of Auschwitz and Daddy, since you must submit only one question at a time. For more information on these themes, please follow the link below for further analysis of the poem, or submit a new question to the Lady Lazarus Group.