Boda, Spanish for “wedding,” comes from the Latin word votum, meaning a “vote, promise”.
This, indeed, makes sense: what is a wedding if not just a vote in the other person, and a promise to be with them? At least in Spanish it is. (The other word for wedding in Spanish, casamiento, is related to the Spanish for “home”, casa).
This one isn’t obvious, at all, based on the spelling, but it is based on the sound. One lesson is to guess parallel words based on the sounds more than the letters. But pay attention to the letters when they are unexpected or voiced weirdly.