y-3=0
Solve it for y
y = 3
That's the same as
y = 0x + 3
[That's hard to recognize because the 0x is understood, not written]
Compare it to
y = mx + b
So it has a slope of m=0, and y-intercept of (0,b) = (0,3).
So it is a horizontal line with y-intercept (0,3)
Since it is horizontal it is parallel to the x-axis, and will
never intersect it. Therefore it has only a y-intercept (0,3)
and it has no x-intercept.
Edwin