What the means of super() using x++ in d365fo

It is the core functionality will call the Kernel Level method of the current (update)method.

For ex: 

Public void update()

{

super();

}

Once the super has called, 

• The actual functionality will execute.
• Execute the core process of current methods.
• It is constructor (call main functionality of method).

If we have written something below the super, then after updating the record our code will execute.

If we have written something above the super, then before updating the record our code will execute.