If you want to target ads to only people who speak Spanish, you can:
write your ad and keywords in Spanish and target the Spanish language
have Google translate your ad and keyword into Spanish
in your ad text, make a reference to Spanish speakers
write your ad and keywords in English and target the Spanish language
Explanation: If you try to communicate with others who don’t speak the same language, you might find it tough to get your message across. Similarly with AdWords, you want your ads to appear for customers who can understand them. Your ads can appear for customers who use Google products and third-party websites in the languages that your campaign targets. This helps ensure that your ads will appear on sites that are written in the language of the customers you’d like to reach.