The English word hell does not come from Old Norse, but it is etymologically cognate to Old Norse word hel. (If two words are cognate, that means that they derive from a common root.)

English and Old Norse both belong to the Germanic branch of the Indo-European language family. Both languages are descended from Proto-Germanic, which, in turn, is ultimately derived from the Proto-Indo-European language. The Proto-Indo-European verbal root *ḱel- means "to cover" or "to conceal." In Proto-Germanic, this root gives rise to the word *haljō, which means "concealed place" or "underworld." Both the English word hell and the Old Norse word hel derive from this common root.

The root *ḱel- also gave rise to the Proto-Germanic word *helmaz, which means "helmet" (since a person's helmet covers their head). This, in turn, is the root of the Modern English words helm and helmet. Thus the words hell and helmet are etymologically cognate.