It is a linear function. We need only two points to plot the graph.
Choice any two values of x. Put them to the equation and calculate the values of y.
y = 2x + 3
for x = 2 → y = 2(2) + 3 = 4 + 3 = 7 → (2, 7)
for x = -2 → y= 2(-2) + 3 = -4 + 3 = -1 → (-2, -1)
Look at the picture.