The equation of the line is in slope-intercept form. The slope is the coefficient of x, 1/3. The y-intercept is the added constant, -1.
These mean the line goes through the point (0, -1) on the y-axis and increases by 1 unit vertically for every 3 units of positive horiontal movement. These facts can help you draw the graph.
The steps are:
identify the y-intercept on the coordinate plane
find a point that is 3 units to the right and 1 unit up