It's a variation of a Fischer's or Lilian's Lovebird. You may want to check for lost and found animals in your area. He could be someone's escaped pet. If no one claims it, you have a new buddy!

I live in a huge apartment building and it flew in thru our balcony earlier so we are keeping it ! Its very friendly we named him Mango but not definitely sure what breed he is.. Someone Plz help ! Thank yu !