Hence means from this reason, or from this place. Hence the delay, three years hence, get thee hence.
The reason sense is the live one and it needs no verb — hence the delay is a complete sentence in practice. The time use, meaning from now, is formal. The place sense is archaic. Note thence, meaning from there, and whence, meaning from where.
1adverbhenceFrom this reason.
“The shop is closing down, hence all the big discounts.”
2adverbtimeFrom this time.
“The new rules will come into force two years hence.”
Too few real examples of this word to estimate which sense is commonest.
hence is a connective.
Middle English hennes comes from Old English heonan, away or from here, with an added -s that later became -ce.
Proto-Germanic
*hiz
Proto-West Germanic
*hin-
Old English
heonan — away", "hence
English, today
hence
A later Middle English - spelling, retaining the voiceless -s, of hennes (henne + adverbial genitive ending -s), from Old English heonan (“away", "hence”), from a Proto-West Germanic hin-, from Proto-Germanic hiz, and Proto-Germanic -anē. Cognate with Old Saxon hinan, Old High German hinnan (German hinnen), Dutch heen, Swedish hän. Related to Old English her (“here”).
Etymology from Wiktionary, CC BY-SA