si

if, whether; points out a contradiction (and often implies that it's obvious or that it's easy to find out about)

“Se podría estimar, entonces, que Tesla probablemente vendió entre 5.000 y 6.000 Cybertrucks en el segundo trimestre si las tendencias de consumo se mantuvieron estables.” — It could be estimated, then, that Tesla probably sold between 5,000 and 6,000 Cybertrucks in the second quarter if consumer trends remained stable.

Etymology tree Proto-Indo-European *sóder. Proto-Italic *sei Latin si Spanish si Inherited from Latin si (“if”).