when x>=6; (x-6) is >=0 so y=x-6
when x<6 (x-6) is negative so y=-(x-6)
but our y is 6 greater then the y we have looked at above so:
y.= x-6+6, ..when x>=6
..= -x+6+6, when x<6
y.= x, ........when x>=6
..= -x+12, ..when x<6
which you should be able to sketch.