The word "out" is used with many different idioms and expressions and can have many different meanings as an adjective or as an adverb.
For example, the sentence, "He's out" could mean...
1. He's a baseball player playing offense, and he has to leave the field.
2. He's openly gay (homosexual). Instead of keeping it a secret, he tells people the truth about himself.
3. He's no longer a part of the organization. Someone fired him, told him to leave, or decided not to include him in something.
4. He's not in the office. He's out at lunch, or he's doing some other activity outside the office.