Translation:How many white togas are in the shop?
They had "fullonica" = laundries, that offered several kinds of services, so I guess it was made there.
In special circumstances additional treatments could be procured, such as sulphuring and chalking. Sulphuring involved spreading the textiles over a specially formed installation of twigs. Sulphur dioxide was burnt under the installation, infusing the fabric. This served to make the fabric even more lustrous, and may have also helped with whitening.
I still don't know how were their clothes shop, and who bought there and who made their clothes themselves or hired slaves. I guess the poorer ones made their clothes themselves, with low quality materials, and the richer were the ones buying from stores.
If someone could explain me how this clothes market works...