This is the 2713th most frequent Polish word.
dodatkową
"Additional."
Here, 'dodatkową' is a singular feminine adjective describing 'kopię', indicating an additional item.
Proszę dodać dodatkową kopię do zamówienia.
Please add an additional copy to the order.
In this sentence, 'dodatkową' modifies 'pracę', showing extra work or responsibility.
Mam dodatkową pracę do wykonania.
I have extra work to do.
In this example, 'dodatkową' is describing 'porcję', referring to an additional serving.