The Institute of the Brothers of the Christian Schools, their correct name, is a religious congregation. Their function is to teach.They do not ordain members. Therefore, all are brothers.
The obligation to recite the the Divine Office is not reserved to priests. Members of institutes of consecrated life are obliged to say the Office, too. As the De La Salle brothers have the external, active apostolate of teaching they are not bound to the full choral office like, say, monastics are.
I used to work in a De La Salle college and was very happy there. The few brothers I knew were extremely nice men and very good teachers.