You are looking at TypeScript. There is 1 parameter, which is an Object. That's the 1st {}. Then there is a colon and another object... but that stuff after the colon is not another key:value object it is the definition of the 1st object. It's saying the 1st object must have a "config" key and the value of the config key is a "ConditionalFormattingConfig" whatever that is. And it must have an "onChange" key that takes a function that accepts a 'config' parameter (of type ConditionalFormattingConfig) and returns nothing (void). Etc....

And back to the 1st parameter, instead of using a variable name for the parameter this function takes, it is using something called "object destructuring". So instead of asking for a variable called params and then accessing it as "params.config", they are pulling the keys out of the object into variables.

// You can do this
function doSomething(params) {
  doSomethingWith(params.config)
}

// This is the same with object destructuring
function doSomething({config}) {
  doSomethingWith(config)
}

const myObject = {config: 'fast'}
doSomething(myObject)

Hope that clears things up.