Can anyone tell me what bun does and what’s the hype about, like if I have a vue project does bun build it for me and make it faster? Or it’s just for backend code optimization

Bun is great on burgers.
On code, though? No idea.

@Root don’t forget hotdogs! Mmmmmmmm burgers. Anyway to answer the question, as long as there’s beef paddies, cheese, lettuce tomato, onions and most importantly ketchup between them, buns are useful. Otherwise they’re semi stale bread from the grocery store

It’s just a nodejs replacement thingy similar to deno

If you were to drop your Vue single file components through just the vue-compiler, it would not do anything besides its scope. That's why you use a bundler like Bun, Vite or Rollup.