The equation of a line represents the relationship between two variables. If we know one of the variables (x or y) then we can find the other variable.
a) A point on the x-axis means that y=0. Put y=0 in the equation and solve for x. x=4/3
b) A point on the y-axis mean that x=0. Put x=0 in the equation and y=-4.
You can now use these points to draw line on a cartesian plane. Take a look at the attached photo.