"Sten" might be a misspelling of "skin" (character or weapon cosmetics) or possibly a specific mod/hack name — but it's not a standard term in the official 1v1lol community. It could also refer to the STEN submachine gun from other games, though 1v1lol doesn't feature real-world gun names like that in its official version.
If you want a different format (longer article, SEO meta tags, or a how-to gameplay guide), tell me which and I’ll draft it. 1v1lol sten unblocked full