For tennis scholarships, there are several levels:
NCAA Division I tennis, several scholarships available
NCAA Division II tennis, Maximum of three full scholarships
NCAA Division III tennis, No scholarships
NAIA several scholarships available
Scholarships can be split into two players or more (each player gets half a scholarship).
Not all schools have their scholarships funded, the list above is the maximum number allowed, but there can be fewer. Scholarships come from the College foundations, which are made up of sports boosters, graduates, etc.