What does "write me a new minivan" mean here?
PS: I am from a non English Speaking country.
The goal is to "write bug-free software", so the man is saying he is going to "write" himself a new minivan by fixing the bugs in the code. Essentially, he is going to make enough money by writing bug-free code that he will have written enough to purchase himself a new minivan.
Wally, the engineer who is going "write a mini-van", is going to intentionally abuse the incentive system by intentionally creating bugs, then claiming the ten-dollar bonus for fixing each bug. That can be done much faster than finding and fixing existing bugs, so it's a quick way to "earn" enough money to buy a minivan.
The larger point of the comic is that misaligned incentives create bad behavior, and that the people who create misaligned incentives don't realize when they do so: