The phrase "to seal the jar" means to close or cover the jar tightly to prevent air, moisture, or anything else from entering or escaping. Full definition
You can also keep it in tightly sealed jars in your refrigerator for a couple of weeks. (fieryfoodscentral.com)
You can store sealed jars of salad in the refrigerator for up to a month or so, once the seal has been broken, it will keep for up to 1 month. (kimberlysnyder.com)
Stir in the probiotic powder, seal the jar with a lid, then wrap the jar in a towel to keep it insulated. (detoxinista.com)