She sizes him up one last time, as if confirming that she does indeed trust him, and then nods.

The rope slung around her shoulder is attached to a grappling hook; she stands back to aim and throw it over the balcony railing. A preliminary tug doesn't reveal anything too immediately alarming, and so up on the rope she goes.

She's clearly done this before, but that doesn't mean much if the balcony doesn't hold.