Hi, Junko from Japan here. The Japanese word SHINE (not meant glittering shining, but SHI-NE) means “die.” It’s an imperative sentence of the verb SHINU. I think you’ve heard that many times in Japanese anime and manga.

Does it directly mean “you should die”?

Yes. It’s a common phrase to insult or offend someone. Though I’m not sure if I can say it’s common…
In anime and manga, characters often say SHINE! when they fight and attack their opponents. If you say SHINE to a Japanese, it’s 100% abusive.
I think people are becoming using this phrase more easily affected by battle and Furyo (punk kids) animes. But don’t use it carelessly. It’s a clearly dirty and offensive word. We never regard it as a joke.
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