Why does a callback function parameter change the output

JavaScript
1

Blockquote
Step 7 Passed (Number Sorter)
You need to get the values from your select elements. These values will currently be strings and you will convert them into numbers.
Use the map function to iterate over the array. Pass a callback function to map that takes a dropdown parameter and returns dropdown.value.

I passed this step but having trouble understanding this:

The step I am on

const sortInputArray = (event) => {
  event.preventDefault();
  const inputValues = [...document.getElementsByClassName("values-dropdown")].map((something) => (something.value));
  console.log(inputValues);

The console shows: [ ‘8’, ‘2’, ‘4’, ‘1’, ‘3’ ]

  const inputValues = [...document.getElementsByClassName("values-dropdown")];
  console.log(inputValues)

Provides all possible select values as objects within an array which makes sense.

The part that I am not getting is why does mapping a previously undefined callback function automatically determine what information is in the select boxes without explicity linking the select box .value individually? Sorry for poorly articulating this, thanks in advance.

2

Nevermind, i get it! The .value is what provides the info for the individual boxes. Thanks