1.
cast-off skin; empty shell
The shed skin of an insect or snake. Literally, the shell left behind after a creature has emerged from it.
2.
empty shell of a person; lifeless state
A person who has lost their energy, spirit, or motivation and seems hollow or absent. Used figuratively.
Usage
Sense 1 is literal — the shed exoskeleton of insects (especially cicadas) or snakeskin. Collecting cicada shells (蝉の抜け殻) is a common childhood activity in Japan. Sense 2 is figurative, describing someone who seems hollow or devoid of energy.
Common collocations
Cultural note
A 蛇の抜け殻 (shed snakeskin) is traditionally believed to bring good luck with money in Japan. Some people keep one in their wallet.