* "tu vas bien" literally means "you go well" but it's used as "how are you?" or "are you doing okay?"
* "ton travail" means "your work"
* "ça marche" means "it works" or "it's going well"
Considering the context, the whole phrase could be interpreted as:
"How are you? Is your work going well?"
It's a friendly, informal way to inquire about someone's well-being and their work.