Are there any major indicators to tell if a bird is happy or not? Im a full time university student and i really love my bird so i let he/she out in all my spare time, but i dont know if he/she is as happy as he/she could be. Im wondering if he/she misses other birds etc

Also Lutino doesnt talk much, does this mean anything?, he/she is 5 months. Although i do think lutino is trying to talk because he/she makes these gentle muttering/mumbling sounds.
Please reply if you have any comments at all
Thanks
-Sarah