This is the 10446th most frequent Polish word.
czterodniowego
"Of a four-day duration."
The word "czterodniowego" is used here as an adjective in the possessive case (genitive) to describe the duration of the training program.
Wziąłem udział w czterodniowego szkoleniu o zarządzaniu czasem.
I participated in a four-day training on time management.
Here, "czterodniowego" serves as an adjective in the genitive singular form modifying "pobytu" (stay), indicating the duration of the stay.
Jego plan podróży uwzględnia czterodniowego pobytu nad morzem.
His travel plan includes a four-day stay by the sea.
In this example, "czterodniowego" is modifying "przygotowania" (preparation), highlighting the time span allotted for preparations.