This is the 16347th most frequent Polish word.
uzupełnianiu
The act of completing or supplementing.
In this sentence, 'uzupełnianiu' refers to the act of completing or filling out documents.
Podczas uzupełnianiu dokumentów zauważyłem brak jednej strony.
While filling out the documents, I noticed one page missing.
Here, 'uzupełnianiu' is used in the context of populating or completing tables with data.
Mam trudności w uzupełnianiu tabel w Arkuszach Google.
I have difficulties in filling in the tables in Google Sheets.
In this case, 'uzupełnianiu' denotes the act of providing or completing missing information.