If f(x)=ax²+bx=c
then the zeros of f are the roots of the equation:
ax²+bx+c=0 ;

if the zeros are real they are the x intercepts of the graph of f.
if a quadratic equation has two real roots, the corresponding quadratic function has two real zeros and its graph intersects the x axis at two distinct points.

if the function has one real zero, the graph intersects the x axis at a single point .

if the function has two imaginary zeros, the graph does not intersect the x axis.