Javascript: when new a Promise instance, where are the parameters(resolve,reject) from

Question

when I learn the concept about Promise, I see the below sample code.

new Promise( (resolve,reject) => { // who pass this two function resolve and reject ??
    setTimeout( () => {
        resolve("find this paramter function");
    }, 5000)
})

" when new a Promise instance, where are the parameters(resolve,reject) from ?? "

The above question bothers me a lot, so I want to understand it. Thanks in advance.