This is the 17146th most frequent Russian word.
старух
"Старух" is not a correct Russian word. You may have meant "старуха," which translates to "old woman" or "elderly woman."
The word 'старуха' is used here as a noun to denote an elderly woman in a neutral narrative context.
Там сидела старуха, разглядывая фотографию.
There was an old woman sitting there, looking at a photograph.
In this sentence, 'старуха' is used in the dative case 'старухе', indicating to whom the action of helping is directed.
Я помог старухе перейти через дорогу.
I helped the old woman cross the street.
Here, 'старуха' is the subject and is used in the nominative case, presenting the elderly woman as the one performing the action of storytelling.