A vos marques! Prêts? Partez!
ah vo MAARK! pray? paar-TAY! Click below to hear this pronounced.
On your marks, get set, go!
Or Ready, steady, go, if you speak British English. Or one, two, three, go.
A is written à in lower case. It looks strange to perch an accent on top of a pointy capital letter, but the word really has the accent on it, to distinguish it from a, part of the verb avoir (to have). The preposition à normally means in or at, but also on in this case.
I had never thought of the second element as a question, but here it is. Are you ready? Not that anyone ever says no! Will they stop the race while you tie your shoe? You should have thought of that beforehand! Prêts will always be plural in this context, because you can’t have a race with only one person. But if it’s a women’s team, it will be Prêtes, using the feminine form.
And partez: literally, leave! Allez, go, is a much more general word. It doesn’t tell you in which direction to move, what your goal is, how to get there. It is so general that it is also used to mean nothing at all, as in Allez, viens! It looks like Go, come! but really just means Come on!
Is it less precise to start a race with a two-syllable word, partez, instead of a one-syllable word like go? Do runners get confused about whether to start on the first syllable or the second? I doubt it. Maybe that’s why they use starting guns. I leave you with that absolutely useless thought!