If y=2 that means that your slope m=0.  Therefore any value you substitute for x into the equation y=mx + b will give you the value y=2.  This also means that 2 is equal to b, your y-intercept.  If your slope is 0 then, you have a horizontal line at y=2, so any value of (x,2) will be a solution to this problem, because your y-value will ALWAYS be 2, because 0 multplied by any number will provide 0. So subsitute your values for m and b into the slope intercept equation, and you’ll see y=2, no matter what x you decide to substitute:

y= mx + b
  = 0x + 2
  = 2
So if I choose x to equal 3, 6, or 5 and substitute them individually into the equation for x to find y, my solutions would always give y=2.

y= mx + b
y=  0(3) +2
y= 2

Do the same with 5 and 6 and your results should be:
(3,2)
(5,2)
(6,2)