The phrase "several ounces" means a few or more than two ounces. It is a measurement used to describe the weight of an object or substance. Full definition
This was not nearly enough to feed my daughter, who was drinking several ounces of formula at each feeding. (babycenter.com)
Babies should gain several ounces within 24 hours and if they don't there may be something wrong. (siriusdog.com)
Women can collect as much as 1/2 - 1 ounce per breast at each feed, and some mothers have obtained several ounces at a feed. (motheringfromtheheart.com)