This is the 4831st most frequent Polish word.
opakowaniu
"In the packaging."
The word 'opakowaniu' is used here to specify a location, inside the package, showing the containment aspect of packaging.
Zostawiłem instrukcję obsługi w opakowaniu.
I left the manual inside the package.
Here, 'opakowaniu' is used to refer to the packaging of hot chocolate, illustrating a use case in identifying a container or form of packaging for an item.
Kupuję gorącą czekoladę w opakowaniu.
I am buying hot chocolate in a package.
In this sentence, 'opakowaniu' indicates a surface on which information might be located, such as the printed exterior of a package.