You could say that it is "three one twelfths," or 3 twelfths, which simplifies to 1/4.
Mathematically, you multiply the numerators and denominators together, so it would be
\(\frac{1}{12} * \frac{3}{1}\)
\(\frac{1*3}{12*1}\)
\(\frac{3}{12}\)
\(\frac{1}{4}\)
