Bottle contains: 30ml with 8.5mg CBD/ml (255ml per bottle)
A tincture is a type of medicine, using a medium such as alcohol or grape seed oil to extract the cannabinoids from the plant. Tinctures can be ingested in maybe different ways, the quickest onset being under the tongue, but can be mixed into a drink or food. When using potent remedies like this it's a good idea to get advise from a physician.
Typically 1-2 drops under the tongue is a safe dosage, but can be increased as you feel comfortable.