The second moment of area is a value which—given an origin—describes how point masses are distributed around that origin. (i.e. a number for how point masses are distributed). It is in units m^{4}. Take, for instance, the following picture: We have defined an origin at (0,0) of the figure above. Furthermore, we have some \rho_{i} which is the distance from that origin to each of the infinitesimal areas \dd{A}. Then, the second moment of area is defined as:
\begin{equation} I = \iint_{R} \rho^{2} \dd{A} \end{equation}
This… would make sense.