han

used to form the present perfect tense of verbs, indicating an action that happened at an unspecified time before now or recently completed actions

han + participio

• have done

• They have just arrived.

  Han llegado hace poco.

used to form the past simple tense of verbs, indicating an action that happened in the past and is now complete

han + verbo en pasado

• had done

• They had already left when we arrived.

  Ya se habían ido cuando llegamos.