Just look at all the definitions in El Diccionario de la Real Academia Espaola (Dictionary of the Royal Spanish Academy). It can be a conjunction, preposition, adverb, linking word, interjection, or a noun.
Just look at all the definitions in El Diccionario de la Real Academia Espaola (Dictionary of the Royal Spanish Academy). It can be a conjunction, preposition, adverb, linking word, interjection, or a noun.