Why do I need to know what allez-y and vas-y mean?
It's hard to overstate how useful allez-y and vas-y are in colloquial French conversation.
They are a great way to make your spoken French sound more natural and native and also — once you understand what it means — you won't be left behind (literally) when someone says it you.
So, what do they mean?
Allez-y and vas-y are the polite (or plural) and informal (or singular) versions of the same expression.
They mean 'Go!', 'Go on!', 'Go ahead!', 'Be my guest!', 'Go for it!' or even 'Knock yourself out!'.
You'll often hear the more polite form — allez-y — used by waiters when they're ready to take your order.
So, for example once a waiter has checked that everyone at your table is ready to order, they might say: Allez-y, je vous écoute — 'Go ahead, I'm listening'.
Also, you might say it to one of your neighbours if you're holding the lift door for them.
For example, Allez-y. Après vous. — Go ahead. After you.
Meanwhile, the more casual — or singular — form vas-y is used in exactly the same way but with young children or friends.
For example, if you are encouraging your child in a race, you might say: Vas-y, cours! — 'Go on, run!
Allez-y is the most common version you'll hear in France and is made up of the vous form of the verb aller (to go) plus y which means 'there'.
Vas-y on the other hand is made up of the tu form of the verb aller with y tacked on at the end.
When saying allez-y, you can stress the 'z' and when saying vas-y, you pronounce it vah-zee.