This is the 16432nd most frequent Russian word.
рубаха
"Рубаха" - a traditional Russian shirt or blouse.
Here, "рубаха" is used metaphorically in the idiomatic expression "рубаха-парень" (easy-going guy) to describe someone's friendly and approachable nature.
Он такой рубаха-парень, всегда готов прийти на помощь.
He is such an easy-going guy, always ready to help.
In this sentence, "рубаха" refers to a traditional Russian-shirt, emphasizing its cultural and historical identity.
На ярмарке продавали старинную русскую рубаху.
At the fair, they sold an antique Russian shirt.
Here, "рубаха" is simply used to mean a shirt, demonstrating its standard, everyday usage.