This is the 8625th most frequent Russian word.
осипову
"Осипову" is the dative or accusative form of the Russian surname "Осипов," typically meaning "to Osipov" or "Osipov" as a recipient.
Using "Осипову" here denotes the dative case, indicating to whom the letter was handed.
Я передал письмо Осипову.
I handed the letter to Osipov.
Here "Осипову" is also in dative case, indicating the recipient of the report.
Мы послали Осипову отчет.
We sent Osipov the report.
The word "Осипову" in this usage is in dative case, showing to whom gratitude should be directed.