Can you make me more clear about In-place operators?

Answer 1

It would be better if you can provide us with the code snippet you're unable to understand.

in-place operators are also known as shorthand operators.

x += y is same as x = x + y.
x -= y is same as x = x - y.
x /= y is same as x = x / y.

Answer 2

thank you
I think I got it.