Breakdown of Врач говорит, что рану нужно промывать водой каждый день.
Questions & Answers about Врач говорит, что рану нужно промывать водой каждый день.
Because рану is the accusative singular form of рана (wound).
In this sentence, the wound is the direct object of промывать (to rinse / wash / clean repeatedly), so Russian uses the accusative:
- рана = nominative, the basic dictionary form
- рану = accusative, used for the thing being treated
Since рана is a feminine noun ending in -а, its accusative singular changes to -у.
Что means that here.
It connects the two parts of the sentence:
- Врач говорит = The doctor says
- что рану нужно промывать водой каждый день = that the wound needs to be rinsed with water every day
So it works just like English that in a sentence like The doctor says that...