Answer
$y=2$
Work Step by Step
Using $y-y_1=m(x-x_1)$ or the Point-Slope Form of linear equations, the equation of the line with the given conditions,
\begin{array}{l}\require{cancel}
y_1=2
,\\x_1=0
,\\m=0
,\end{array}
is
\begin{array}{l}\require{cancel}
y-2&=0(x-0)
\\
y-2&=0
\end{array}
In the form $Ax+By=C$ or the Standard Form of Linear Equations, the equation above is equivalent to
\begin{align*}
y-2+2&=0+2
\\
y&=2
\end{align*}