Answer
Please see below.
Work Step by Step
Please note that the absolute value for sine and cosine removes the lower half of the graph, which is below the $x$-axis, and flips it above. This results in two complete cycles, where there had been one.
So, since the period of $3\sin \pi x$ is $\frac{2\pi }{\pi }=2$, the period of $y=- \left |3 \sin \pi x \right |$ will become $\frac{2 }{2}=1$.
