The equation of the line is in the form of
Y = 'S'x + 'P'
Whenever the equation of the line is written in that form, you can read
the y-intercept straight from it. In that form, the 'P' is the y-intercept.
In the equation in your question, the y-intercept is -2 .
When you draw the graph of that equation, it will cross the y-axis at y = -2.