Simplify the following text for a Grade 11 native English-speaking person.
Original: Kwanzaa celebrates what its founder called the seven principles of Kwanzaa , or Nguzo Saba ( originally Nguzu Sabaâ '' the seven principles of blackness ) , which Karenga said `` is a communitarian African philosophy , '' consisting of what Karenga called `` the best of African thought and practice in constant exchange with the world . ''
Simplified: Kwanzaa celebrates what its founder called the seven principles of Kwanzaa , or Nguzo Saba ( originally Nguzu Sabaâ '' the seven principles of blackness ) . Karenga said that this `` is a communitarian African philosophy , '' .