For three non-zero vectors $a$, $b$ and $c$, the scalar triple product $a \cdot (b \times c)$ measures which quantity?

$b\times c$ is normal to the plane of $b$ and $c$ and has magnitude equal to the area of the parallelogram they span. Taking the scalar product with $a$ multiplies that area by the height of $a$ above the plane, which is the volume of the parallelepiped with $a$, $b$ and $c$ as its edges. Here the volume is $|36| = 36$ cubic units, and because the value is not zero the three vectors are not coplanar.