If you are launching a business in Spain and don’t intend to expand beyond this country, it would be a very good idea to get the .es domain suffix as Google and other search engines give preference to such domains in geolocated searches.
That means that with all other things being equal, if a user searches from Spain, Google will give more prominence to mydomain.es than to mydomain.com.
Registering a .es domain is quite straightforward.
You can go to the government’s own website that handles registrations, however, I would not recommend it as it’s a hassle to register there and it’s not that user-friendly.
I would instead recommend any of the following registrars:
The Registrant, Technical and Billing Contacts of an .ES domain name may either be a natural person/individual or a company. The Admin Contact must be a natural person/individual only.
While registering a .ES domain, you need to provide an identification number (DNI/NIE/passport), and if registering as a business, the VAT number.
The cost of .es domains is usually between 10 and 15 Euro depending on the registrar, and it is renewed every year.