Been" is a past participle of the verb "be," which is used to indicate that an action or state has occurred or existed in the past.
It is often used in the present perfect tense, which is formed by combining the present tense of the verb "have" with the past participle of the main verb. For example, "I have been to Paris" means that the speaker has gone to Paris at some point in the past and may or may not be there now.
It can also be used in the past participle with helping verbs such as "has, had, have" to indicate an action completed in the past.