I dont get it .... what

Tell us what’s happening:
what does this have to do with destructuring or commas?

Your code so far

let a = 8, b = 6;
// Only change code below this line
[ a, b] = [b, a];

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Challenge: Use Destructuring Assignment to Assign Variables from Arrays

Link to the challenge:

I suggest you read the explanations again.

However, what you are doing here with destructuring is swapping out the variables.

If you do a = b; b = a; , you get a wrong result. So, destructuring is the way here.

You will find and example similar to the challenge Here