Been is the past participle of the verb “to be,” which means it's the form you use with helping verbs like “have” or “has” to show that something happened or existed in the past and connects to the present.

When you say “I have been to the Grand Canyon,” you're telling someone about a past experience that matters now (maybe because you're looking at photos or planning another trip). When your teacher says “You have been working hard,” she's recognizing effort that started earlier and continues to make a difference.

You'll often hear been in phrases like “has been,” “have been,” or “had been.” For example: “She has been my best friend since kindergarten” shows a friendship that started in the past and still exists today. “The library has been closed all week” connects past closures to the present situation.

Notice that been feels different from the simple past tense. “I went to the museum” just states a past fact, but “I have been to the museum” suggests that experience is somehow relevant right now, perhaps because you're recommending it to a friend or remembering what you saw there.