This is the 16402nd most frequent Polish word.
warstwie
"Warstwie" means "layer" or "stratum" in English.
The word 'warstwie' here is used in the locative case, describing something located within the 'layer'.
W górnej warstwie znajduje się najwięcej wilgoci.
In the upper layer, there is the most moisture.
The word 'warstwie' is in the locative case indicating the application on a 'layer'.
Dodajemy wosk pszczeli w cieńszej warstwie na drewno.
We apply beeswax in a thinner layer onto the wood.
Here 'warstwie' denotes levels as metaphorical 'layers' in the locative case.