Are and were are forms of  “to be” in the present and past tense respectively, and are used with 2nd person singular, and 1st, 2nd, and 3rd person plural.

• Present, 2nd sing.: You are late. (you = one person)
• Present, 1st, 2nd, 3rd plur.: We are late. You two are late. They are late.

• Past, 2nd sing.: You were late.  (you = one person)
• Past, 1st, 2nd, 3rd plur.: We were late. You two were late. They were late.