Answer
$$y = 3$$
Work Step by Step
$$\eqalign{
& \ell {\text{ is parallel to the }}x{\text{ - axis}}{\text{, then the line }}\ell {\text{ has the same slope}} \cr
& {\text{that the }}x{\text{ - axis}}{\text{, the slope of the }}x{\text{ - axis is }}0 \cr
& m = 0 \cr
& {\text{The line passes through the point }}\underbrace {\left( {2,3} \right)}_{\left( {{x_1},{y_1}} \right)} \cr
& {\text{Use the point - slope form of the equation of a line}} \cr
& y - {y_1} = m\left( {x - {x_1}} \right) \cr
& y - 3 = 0\left( {x - 3} \right) \cr
& y - 3 = 0 \cr
& y = 3 \cr} $$
