Answer
(refer to the step by step part for the explanation)
$\\$The graph of $y=b$ is a line whose points all have a y-value of $b$. All these points belong to a horizontal line.
Work Step by Step
$y=b$ can be written as $y= 0x + b$
$\\$This means that for whatever value of $x$, the value of $y$ is always going to be $b$.
$\\\\$Thus, the points $(-1,b), (0, b), \text{ and } (1, b)$ are all in the graph of $y=b$.
$\\\\$Connecting the points together to graph the line forms a horizontal line.
$\\\\$Therefore in general, all equations of the form $y=b$, where $b$ is any real number, is a horizontal line.
