my 7th grade son was suspended for 2 days and 2 weeks off the soccer team for "racial remarks" made at lunch. 3 boys from a table behind my sons said

The problem is gong to be whether the principal believes your son, and the people sitting at his table, or the 3 boys sitting behind your son.  If the only thing the principal is relying on is that 3 boys said they heard your son make remarks, and there are other boys who said he did not make such a remark, then definitely fight the suspension.  If there is no history of your son saying things like that, and no history of him being dishonest, why is the principal believing the other boys over what your son is saying?