What does the graph of y=2x^2 look like?
It looks like a parabola of course.
It opens up (holds water) because as x gets big positive or negative, y gets big.
y is never negative since x^2 is never negative.
It goes through (0,0)
Since that is as low as it goes, (0,0) is the vertex and the y axis is the axis of symmetry.