It is not I told to code on vJASS

But if you use one vJASS feature why not using the others xD ?
So for your questions now :
What you pointed is used with structs.
struct Point //Struct are used to define new variable types by using many basic types.
real x
real y
endstruct
function Someting takes nothing returns nothing
local Point p = Point.create() //I create a new Point variable
set p.x = 42 //I change the value x of my Point variable
set p.y = -23 //I change the value y of my Point variable
//Do whatever you want
call p.destroy() //When I don't need this anymore I destroy the variable
endfunction