firma
ES [ˈfiɾma] · Spanish for “signature” · same spelling as Czech firma (a company)
Ask a Czech what firma means and the answer is company - it’s the word on every invoice and shopfront back home. So a Spanish form with a box marked firma looks like it is asking where you work, when all it wants is your signature at the bottom.
Both are the same word, from Latin firmare, “to make firm, to confirm” (from firmus, “solid”). Signing your name is how you confirm something - you make it firm - so in Spanish la firma became the signature. The business sense grew from the same act: a merchant's firma was the confirmed name he signed under, and that travelled through Italian trade into German Firma and Czech firma, the company. English carries both threads - a firm is a company, while firm, confirm and affirm keep the older “solid” sense. Spanish keeps a foot in each: a firma de abogados is a law firm. A signature and a corporation, both just something made firm.