In Spain, there are several languages spoken due to its diverse cultural and regional identities. However the four main languages spoken in Spain are:

Spanish (Castilian): This is the official language of the entire country and is spoken by the majority of the population.

Catalan: Spoken primarily in Catalonia, Valencia, and the Balearic Islands.

Galician: Spoken in the region of Galicia in the northwest of Spain.

Basque: Spoken in the Basque Country and parts of Navarre in northern Spain.

Additionally, there are smaller linguistic communities and immigrant populations speaking other languages, but these four are the main ones recognized within Spain.

More Info: en.wikipedia.org