Reason:
Start at the y intercept (0,4) which is where the red line crosses the y axis.
Then move up 2 units, and to the right 1 unit to arrive at (1, 6) which is another point on this red line.
The motion of "up 2, right 1" means:
Feel free to use any other two points you prefer and you should get the same result. For instance, you could have started at the x intercept (-2,0) and did the "up 2, right 1" motion to arrive at (-1, 2).