You need to do a two-step post-processing:
This is basically as easy as taking the print and dropping it into a vat of Isopropyl alcohol and vigorously shaking it to get all the liquid resin off. Careful, the resulting contaminated IPA is to be treated as toxic waste.
The reason why you wash the print is to make sure no resin stays on it and cures, distorting the print or altering the measurements.
The next step is just having the item sit in UV light to cure thoroughly, which means either having it sit outside in sunlight or under a UV lamp. Under sunlight, it might take a few hours, under a UV lamp, it depends on how thick the object is and you might need to turn and rotate the printed part. Note that some resins, especially transparent ones, can change their coloration when exposed to sunlight, both during or after curing.
Curing is done to ensure all the resin is fully cured and get the full stiffness out of the print - sometimes prints are still somewhat malleable before giving them time to cure.