Removing fluorescein from the organic phase. During the reaction an amide of fluorescein was made what doesn’t have a color and it does not fluoresces under these conditions. So hopefully, the transparency of the upper layer means something good.
The bottom layer is a dilute (1M) sodium hydroxide solution what reacts with the fluorescein to form the highly fluorescent fluoriescein sodium salt what produces this intense green color in the aqueous phase.
Interesting fact: the acid form of the fluorescein does not emit the characteristic intense green color under UV light, it only emits a yellowish-orange color in high concentrations.