Factor $12=2^{2}\times 3$. Rewrite the square root of the product $\sqrt{2^{2}\times 3}$ as the product of square roots $\sqrt{2^{2}}\sqrt{3}$. Take the square root of $2^{2}$.
$$\frac{2\sqrt{3}|108|}{9}$$
The absolute value of a real number $a$ is $a$ when $a\geq 0$, or $-a$ when $a<0$. The absolute value of $108$ is $108$.
