Explanation:
if there is no typo, then that is
y = 1 + 5 = 6
y = 6
has no term in x.
that means 6 is the constant result of the line function, no matter what x value we pick.
and that means this is a horizontal line (parallel to the x-axis) going through the point y=6 or (0, 6).
remember that the slope is the ratio "y coordinate change / x coordinate change".
but y is not changing at all, the change or difference is always 0 no matter what points we pick on the line.
and so, the slope ratio is always "0/...". and that is 0.
so, the slope of that line is 0.
but if there is a typo, then please know : the slope of a line
y =ax + b
is always a (the factor of x).