It's a race as much as "person from English speaking coubtry" is a race. It encompasses white Spaniards, black Dominicans, and indigenous people from Central and South America who don't necessarily speak Spanish themselves.

There are two dictionary definitions of race: people sharing common biological features, and people in the same ethnic group. The biological features one clearly doesn't work.

An ethnic group is a group of people who share a common cultural background or descent, but the cultures and descents of these people are very different.