Municipalities are the basic territorial and administrative unit. The government of the municipality is known as the town or city council; the councillors of the municipal government are elected by all the people registered as living in that municipality. From among those elected, they choose who will be the mayor or maximum representative of the town council.
The municipal authorities also offer various services to those living in the municipal area: municipal police force, library, street cleaning, refuse collection, monitoring of the provision of drinking water, repair of footpaths and promenades, leisure areas for young people, etc. The town council has its own annual budget, and the income (the financing it needs to offer all those services) comes from different sources, principally: taxes and rates, contributions from the provincial government and loans.
...And finally, here are a couple of questions to consider: What would happen if there weren't enough money to offer all the services the Provincial Government of Gipuzkoa provides? What can and should we do to have those services?