Celtics developed the First XI program to commit to one of its strongest benefits, that is, caring about the development of all the players. Celtics coaches lead and mentor the families involved in this program. Simply put, the program is about the players, not about the club. 

Check out our video explanation of First XI
Wikipedia defines the First XI as “the starting XI in an organization's leading team, particularly a cricket team or association football team. A player who is considered part of the starting XI is often the most proficient in his/her particular position - for example, a football club's leading goal scorer will almost always be selected due to his/her ability and the contribution he/she makes to the team." 

"First eleven" is a reference to the fact that they are the first eleven players selected to play for the team. Below is the First XI team on which Celtics president David Rout played!

First XI players receive the best coaching and training in the area. In addition to soccer training, all First XI teams receive strength/speed/agility from a specialized coach. All coaches involved with First XI teams are proud to educate these dedicated, top-performing athletes.