This is the 6221st most frequent Russian word.
тренеру
"To the coach" (dative case of "тренер").
Here, 'тренеру' is in the dative case, indicating the direction of the action to the coach as the recipient.
Я отдал отчёт тренеру.
I handed the report to the coach.
In this example, 'тренера' is in the genitive case, showing possession or relationship as advice from the coach.
Мне нужен совет от тренера.
I need advice from the coach.
Here, 'тренера' is in the accusative case, serving as the direct object being thanked in the context of the sentence.