The points are:
(0,3) and (4,6)
In each coordinate point, the first number corresponds to the x value, and the second number corresponds to the y value (the value of the function).
For the first point, we have (0,3) which is x=3 and y=f(x)=3.
In function notation this is:
which means that when x=0, the f value is 3.
We do the same for the second point, (4,6), we have x=4 and f(x)=6. In function notation we will have:
which means that when x=4, the f value is 6.