The slope is $-1$. The $y$-intercept is $0$. Refer to the graph below.
Work Step by Step
The slope of the line can be obtained by looking at the coefficient of $x$ in the slope-intercept form. Isolate $y$ to obtain: $x+y=0$ $y=-x$ Thus, the slope is $-1$. By definition, the $y$-intercept is the constant in the slope-intercept form of the equation. For $y=-x$ , the constant is $0$, therefore the $y$-intercept is $0$. Plot the point $(0, 0)$. Then using the slope, which is $-1$, move $1$ unit to the right and $1$ unit down to reach $(1, -1)$. Connect the two points using a straight line to complete the graph. Refer to the graph above.