The intercepts are found by putting x=0 (y-int) and y=0 (x-int) into the parabola equation: y=-(x+1)^2+1.
When x=0, y=-1+1=0; when y=0, (x+1)^2=1, so x+1=±1, and x=-2 and 0.
That gives us 0 as y-int and -2 and 0 as x-ints. The graph is an inverted U shape where the arms of the U intersect the x-axis at -2 and 0, so the U lies to the left of the y axis.
The x value for the vertex is midway between the x intercepts at x=-1 and y=1 (-1,1), and this can also be seen in the term (x+1) as the displacement from the origin.