What is a .es used for?

This is the domain extension for Spain. Anyone can buy and use a .es domain, though it's particularly useful for businesses which trade in Spain, or are thinking of entering the country.

Alternatively, you might want to consider it if your name, your company name, or the word you want to register ends in 'es'. For instance, you could have www.bulldoz.es as an alternative to www.bulldozes.com, or similar.