“Are,” like other forms of the verb “be” (e.g., am, is, was, were), is almost always a stative verb when used as the main verb. This means it describes the subject’s state or condition rather than an action.
It can be used in the continuous tense along with “being” to mean “behaving.” This expresses a temporary action rather than a permanent state or quality.
For example, “they are annoying” means they are always annoying: that is their permanent state. “They are being annoying” means they are not always annoying, but they are behaving in an annoying way at the moment.
“Are” (and other forms of “be”) can also be an auxiliary verb modifying the main verb, which is usually an action verb (e.g., “they are running a marathon”).