Slice and Splice - HELP

can anybody explain this code to me, please

Your code so far


function frankenSplice(arr1, arr2, n) {
  // It's alive. It's alive!
  let arr = arr2.slice()
  arr.splice(n, 0, ...arr1)
  return arr;

}

frankenSplice([1, 2, 3], [4, 5, 6], 1);

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Link to the challenge:
https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/basic-algorithm-scripting/slice-and-splice

Create a copy of arr2

Use splice at index n, remove 0 elements and add in the content of arr1 (splice changes the array on which it is used and return the removed elements)

Return the array called arr