This has got to be at least the third time this question has come up in as many months.
No. It is not illegal discrimination of any kind of you are not hired or lose a job because you cannot speak Spanish. ANYONE can learn to speak Spanish, regardless of their race or ethnic origin; therefore a requirement that Spanish be spoken is not illegal. If you were not hired because you were not of Hispanic origin, THAT would be illegal, but requiring you to speak Spanish is perfectly legal since people of any and all races and ethnic origins can and do speak it.