C'est une forme très familière que je considère un peu comme de l'argot et cela peut aussi dire "fait le" selon le contexte.

Well, when I first started learning French I read that “On y va!” meant “Let’s go (there)!” and that “Vas-y!” was just the more familiar form.

Bonjour "Vas-y" est un idiome c'est à dire une expression que l'on ne peut pas traduire mot à mot. Cela veut dire en effet "let's go". PS : Cette forme n'est pas familière et ce n'est certes pas de l'argot!!!

'vas-y' is *not* 'let's go'. 'va' is the 2nd person imperative form of the verb 'aller'. In english it's like 'go!'. but in French no one says just 'va', to say 'go!' we say 'vas-y'. for example: - je veux aller en Australie. (I want to go to Australia) -vas-y! (go!) well, that example was kind of weird but you get the idea. "Let's go" is "allons-y"...when saying "vas-y" you're just telling someone to do something, the speaker is not included in that action. "Let's go play" is "allons jouer", "go play" = "va jouer". "vas-y" can also be used colloquially to encourage someone to do something. (I guess that's what Marie Hélène and Loic were refering to.) e.g.: -tu crois que je devrais lui demander de sortir avec moi? (do you think I should ask her out?) -mais oui, vas-y! / allez! (= yeah, do it! / go for it!) I hope that made sense. "pas de quoi" is the shortened form of "il n'y a pas de quoi", which is similar to "de rien" (you're welcome)...you can use it when you do someone a favor and they thank you, well instead of saying "de rien" you can also say "il n'y pas de quoi" (literally: there's no reason [for thanking me])...but "de rien" is ok too. e.g.: - merci d'avoir arrosé les plantes en mon absence. (thanks for watering the plants when I was away) - de rien / il n'y a pas de quoi. (you're welcome)

Just thought of this. If anyone wants to throw in a "pas de quoi" explanation, as well, you get brownie points :DD Haha, thanks. Et aussi, si quelqu'un voudrait dire a moi le definition de "pas de quoi," je vous aimerai. Haha, merci!