Question

how do you have a reflection in the x axis, if the shape is already partially in the third and second quadrent of the graph

Answer 1

Its a reflection over an x-axis, whats "positive" goes "negative" and whats "negative" goes "positive" with respect to y.

If a shape $S$ is a subset (made of $P_2\cup P_3$ of quadrants $Q_2,Q_3$ then the part $P_2$ that lies in the second quadrant gets mapped to $Q_3$ and part $P_3$ that lies in third quadrant gets mapped to $Q_2$

Hope this helps.