Are is the plural of "is" and "am," a form of the most common verb "be." He is going, but we are going. Are is also used with you, as in, "Are you going to the movies?"
In English, the forms of be break down like this: "I am; you are; he is; we are; they are; you (more than one of you) are." Are, of course, is only used when you are talking about things that are happening now. When they already happened, the word is were: we are here now, but we were there yesterday. Are is also a metric measurement equal to 100 square meters, but the unit is rarely used these days.