y = 2x + 3 is in "slope-intercept form, which is y = mx + b.
m = slope (gradient)
b = y-intercept (where the line crosses the y axis)
In your equation, slope(m) = 2 and it crosses the y-axis at (0, 3)
If you wish to graph the equation, locate (0, 3) on the y-axis.
Your slope is in the form of
So, from (0, 3), move up 2 units and right 1 unit for to locate your second point (1, 5). Draw the line through these two points, and the linear equation is graphed.