Processing your visa application takes the consulate about 4 weeks. The most lengthy part of the process is collecting all of the documents and securing an appointment. For some consulates it is very difficult to secure an appointment, so it is best to plan ahead.
The documents needed to apply for a student visa are:
National visa application form + photocopy
Original passport + photocopy
One recent passport sized photo (to be attached to the form)
Copy of the acceptance letter from the Spanish University (in Spanish or with Spanish translation)
Evidence of funds (could be a statement from the University describing housing or a notarized letter from your parents assuming financial responsibility)
Proof of health insurance
Medical certificate (only need for stays longer than 180 days)
Express mail envelope with pre-paid stamps addressed to yourself with which the consulate may return your passport with the visa