what does '+=' mean?

Question

and how to use it?

Answer 1

int var = 5;
var += 2;
is the same as
var = var + 2;
so
var = 5 + 2;

Answer 2

x=x+2; which is real meaning

Answer 3

السلام عليكم ورحمة الله وبركاته
int x = 3;
x +=5;
يعني
x= x +5;
x=3+5;
x=8;

Answer 4

x += 2

you are increasing x(your variable or number) about 2