The x-intercepts are where the graph crosses the x-axis, and the y-intercepts are where the graph crosses the y-axis. We find these intercepts when we set one variable to zero. For instance,
y = x^2-10x+25
y-intercept : y = 0^2-10(0) +25
y = 25
x-intercept: 0 = x^2-10x+25
0 = (x - 5) (x - 5)
x = 5