An intercept is the point of intersection. A #y#-intercept is the point that a line (in this case, the line #y=2#) intersects the #y#-axis.
The #y#-intercept for the #y=2# graph is simply the point #(0,2)#.
Typically, to find a #y#-intercept, we would set #x# equal to zero and solve for #y#...But here, we don't have an #x#-term. The given line is #y=2# , which tells us that for any #x#, no matter how infinitely large or small, #y# will always be 2. So, intuitively, we know that when #x# is zero, #y# is 2...giving us the #y#-intercept of #(0,2)#. Note that since this is a horizontal line, there is no #x#-intercept.