The Dimensions command returns a list of dimensions of the specified expression.

$\mathrm{with}\left(\mathrm{MmaTranslator}\left[\mathrm{Mma}\right]\right)\:$

$\mathrm{Dimensions}\left(\mathrm{Matrix}\left(\left[\left[1\,2\right]\,\left[1\,0\right]\right]\right)\right)$

$\left[6\right]$

$\mathrm{with}\left(\mathrm{MmaTranslator}\right)\:$

$\mathrm{FromMma}\left(\mathrm{`Dimensions[\{\{1,\; 2\},\; \{1,0\}\}]`}\,\mathrm{evaluate}\right)$

$\left[2\,2\right]$