are (v.)
present plural indicative of be (q.v.), from Old English earun (Mercian), aron (Northumbrian), from Proto-Germanic *ar-, probably a variant of PIE *es- "to be" (see am). Also from Old Norse cognates.

In 17c. it began to replace be, ben as first person plural present indicative in standard English. The only non-dialectal survival of be in this sense is the powers that be. But in southwest England, we be (in Devonshire us be) remains non-standard idiom as a contradictory positive ("You people aren't speaking correct English." "Oh, yes we be!"), and we be has reappeared in African-American vernacular.
are (n.)
metric unit of square measure, 10 meters on each side (100 square meters), 1819, from French, formed 1795 by decree of the French National Convention, from Latin area "vacant piece of ground" (see area).