For the sake of clarity, this is the info from the National Police Web page.
I have amended the somewhat poor English, in-line with actual practice.
Information regarding crimes can be made in English by calling 902 102 112, from 9 a.m to 9 p.m Monday to Sunday. (One can also do so in Spanish, French, Italian and German, but the times for the latter two are from 9am until 3 pm. ) It is not a free call.
The following crimes can be reported by telephone:
Burglary to any type of premises;
Theft of:-
Personal Property, including by pickpocketing, by an unknown, unseen,
perpetrator
of/or from a vehicle
of documents and/or items
from a property, house, shop, storeroom, etc
Loss of documents or other items
Criminal Damage to property, including motor vehicles, dwellings, etc
Information may be given on the telephone in the above cases.
However, it should be noted that one is required to attend a National Police Station of your choice, anywhere in Spain, within 48 hours, to check the info and, if correct sign the actual crime report. If that is not done, then no crime report exists. It should be noted that the report will of course be in Spanish and note, one cannot be certain that the translation is perfect, so you may want to take a translator with you, or you can that the info is correct. Do not expect a translator to be available at any police station.
Should you not be able to attend within the 48 hours, it is possible for the police to call the 902 number, and have a report reinstated, for up to at least 6 months after the telephone call. It is possible that an individual police officer may not know this, so insist.
Information cannot be given on the telephone in cases of theft from a person, when there is a known perpetrator (known may include that the perpetrator was seen). In such cases, victims are require to go a police station, to make the report. They will use the info you have provided on the telephone to do that, but may ask further questions.
Crime reports may be made directly to the National Police or Guardia Civil, but in a case of a crime, never to the Policia Local.
In Spain, Crimes can also be reported directly to the Courts of First Instant. At a court one would expect to find a translator on duty.
Note: Making any statement to police, courts etc. which is not correct, is a criminal offence. For that reason police will sometimes refuse to take a report from victims who cannot speak Spain well, as any confusion regarding understanding, may inadvertently, lead to something incorrectly being recorded.
Be aware, that unlike say UK, one cannot report a crime to a police officer anywhere but in a police station. Also, if you report something stolen, say a vehicle, which is subsequently recovered, even by the police, you must make a report explaining that the property has been recovered.