The given equation is in the form of a linear equation:

$y = mx + b$

where $m$ represents the slope and $b$ is the y-intercept. In your equation $y = -9x - 1$, the slope $m$ is -9.

So, the slope of the line is -9.

Would you like more details or have any questions about slopes or line equations?

Here are some related questions you might find interesting:

1. What does the slope of a line represent in a graph?
2. How do you find the slope of a line if given two points?
3. What happens to the slope if the equation of the line has a positive slope?
4. How do you graph the equation $y = -9x - 1$?
5. What is the significance of the y-intercept in a linear equation?

Tip: The slope of a line describes its steepness. A negative slope indicates that the line is sloping downwards from left to right.