Yes, if it arrives with the Hague Apostille (or legalised, if your country is not party to the Convention) and, when it is not in Spanish, with a sworn translation. The Spanish notary who receives it must also consider it sufficient for the act being signed.
That is why the text should be drafted in Spain and then executed with that wording by the notary in your country. A power of attorney with vague, generic powers is a common reason for a signing to be postponed.