That means Spanish is required. If they were going to do any pure English programming, that would not be a requirement.The job site says "bilingual."
Every person I know... over a dozen... who has actually been interviewed by them has their Spanish knowledge verified.
My own simple test is "if you hit your finger with a hammer, what is the first word you say?" I ask the question in Spanish, and if the answer is not a word in Spanish, the interview is over.