When programming, you will see an expression like x=x+1 quite often. More similar cases are y=y/4 or z=z*0.125. This is all because " = " has a different meaning in coding. Instead of "equals", it means "assignment". i.e. Assigning the RIGHT hand side of the equation to the LEFT hand side of the equation. In this case, x=x+1 means increasing x by 1 and assigning the value back to x.
Similarly, y=y/4 means reducing y value to 1 quarter of the original. z=z*0.125 means multiplying original z by 0.125 and assigning the product back to z.
As a matter of fact, this type of operations are so frequently used, that we have shortcut operators just for the purpose: