jobs are full-time or part-time, 1500-2500 USD equivalent a month depending on hours, in Spain no degree or TEFL certificate is federally required, although the TEFL certificate is highly recommended and worth the week or two it takes to become accredited.
I assume you’d need to speak Spanish, though?
english schools only want you speaking english in the classroom, and they’ll have school assistants nearby, often in the classroom, to help you out when Spanish may be necessary, either for you or a student.