If you were using a graph to find the zeros, you would see the points where the curve touches the x axis. Those x coordinates are the "zeros" of the function. Although technology is a crutch and leaves one at the mercy of it.
The "zeros" of a function are the x coordinates when the function is equal to zero. The value of x when y=0. This is why graphically, these are the points when the function touches the x axis.
x^2+x=0 factor
x(x+1)=0 this is true when:
x=-1 or 0
So the zeros of the function occur when x=-1 and 0
Or the points (-1, 0) and (0, 0)