It is not Spanish but Latin, is pronounced skélsior, means "superior" and translates as excellent (closer to the original 'excelsus'). There is a Castilianization as an exélsior, but I have the impression that it was popularized from trademarks. As a curiosity, in English it is a way to call the chip precisely by the company that marketed it to fill packaging.
* Only one "like" per meaning and day, the more "likes" the meaning will appear higher in the list
