$y=\frac{ 1 }{ 2 }x-6$
Subtracting is the same as adding the opposite$y=\frac{ 1 }{ 2 }x+\left( -6 \right)$
Since the equation is written in slope-intercept form, $y=mx+b$, identify the slope of the line as the coefficient next to the variable $x$$\begin{array} { l }y=\frac{ 1 }{ 2 }x+\left( -6 \right),& m=\frac{ 1 }{ 2 }\end{array}$
Identify the $y$-intercept of the line as the constant term$\begin{array} { l }y=\frac{ 1 }{ 2 }x+\left( -6 \right),& m=\frac{ 1 }{ 2 },& b=-6\end{array}$
The slope of the line is $m=\frac{ 1 }{ 2 }$ and the $y$-intercept is $b=-6$$\begin{array} { l }m=\frac{ 1 }{ 2 },& b=-6\end{array}$