​Kit data is sometimes presented in molar units without a corresponding volume, e.g. nmol/well. To determine the concentration in this case, you need to divide by this value by the volume of solution in the well.
Check the kit’s protocol booklet for the volume to load into the well; this will be assay dependent.
Most microplate wells are loaded with a volume of around 50µL (which corresponds to 0.05 mL, or 5x10​-5 dm3).