What is the slope of the line on the graph?

We can see that two of the points that the line goes through are  (0, -1)  and  (1, 5)  .

slope of line that goes through   (0, -1)  and  (1, 5)   =  $\frac{\text{rise}}{\text{run}}\,=\,\frac{y_2-y_1}{x_2-x_1}\,=\,\frac{5--1}{1-0}\,=\,\frac{5+1}{1}\,=\,\frac61\,=\,6$

Also, you can count how many units up and right a point on the line is from another to find the slope.

The point  (1, 5)   is  6  units up and  1  unit right from the point  (0, -1)  ,

so the slope is  6/1 ,  which is  6 .