This is the 6618th most frequent Polish word.
dniach
"Dniach" means "days" (in the locative or prepositional case) in English.
The word 'dniach' is used here as a locative case plural form of 'day' (dzień), indicating a time frame when the action will occur.
W ciągu najbliższych dniach odwiedzę Warszawę.
In the coming days, I will visit Warsaw.
In this sentence, 'dniach' again in its locative case plural form specifies the period of work being referred to, emphasizing a challenging time span.
Po trudnych dniach pracy zasługujesz na odpoczynek.
After difficult days of work, you deserve a rest.
This usage of 'dniach' locatively connects the noun 'dzień' to the context of reminiscing past times.