What's wrong with my code? I don't get it

1

// Setup
var a;
var b = 2;

// Only change code below this line
var a = 7;
var b = 7;
a = b;

2

I’m assuming you’re talking about this: https://www.freecodecamp.org/challenges/storing-values-with-the-assignment-operator ?
a and b variables are already declared and there’s no need to assign 7 to the variable b.

Hint

The var is unnecessary since it’s already used above your code.
Second line from the bottom should be deleted.

Solution 
// Setup
var a;
var b = 2;

// Only change code below this line
a = 7;
b = a;