Ok, take Cola for an example. Each bottle should contain 330ml of liquid(cola). On the production line some bottles are filled up to 400, or 450ml of liquid instead. This excess liquid is GIVEAWAY, because they are literally giving it away (since the customer only pays for 330ml).

So the process on the production line is to increase productivity by ensuring that bottles are not overfilled....so that nothing is given away. (i.e. no giveaway)

See the link attached for the same thing explained in a real life case with Muller yogurts.

From link:
"This data enables supervisors to correct the fill heads, to help reduce product giveaway and comply with average weight legislation."