This is the 2583rd most frequent Polish word.
stalowej
"Stalowej" means "steel" (adjective form, genitive or dative singular feminine, or locative singular feminine in Polish).
In this sentence, 'stalowej' describes the material ('steel') as an attributive adjective modifying 'stali' ('steel').
Mam kubek z rączką ze stalowej stali.
I have a mug with a handle made of steel.
'Stalowej' functions here as an attributive descriptor for 'konstrukcji' ('structure'), indicating the material of the structure.
Most stalowej konstrukcji przeszedł inspekcję.
The steel-structured bridge passed the inspection.
Here, 'stalowej' is an attributive adjective describing 'siatki' ('mesh'), showing the composition of the mesh.