This is the 7559th most frequent Polish word.
kurierowi
"To the courier."
The word 'kurierowi' is in the dative case here, indicating the recipient of the action.
Proszę przekazać ten pakunek kurierowi.
Please give this package to the courier.
'Kurierowi' again is in the dative case, suggesting the indirect object who receives payment.
Nie zapomnij zapłacić kurierowi za przesyłkę.
Don't forget to pay the courier for the package.
The dative case 'kurierowi' is used, relating to the indirect involvement of the courier.