What does the “-cie” ending do to Polish verbs?

The poem’s punchline rhymes on grammar: a woman would rather cover dirty nails with polish than wash them — “albo mycie, albo krycie,” either washing or covering. Both words are verbs turned into nouns: “myć” (to wash) becomes “mycie” (the washing), “kryć” (to cover) becomes “krycie” (the covering). This “-cie”/“-nie” ending is one of Polish’s most productive tools for naming any action as a thing.

The pattern is everywhere once you notice it: “czytać” (to read) → “czytanie” (reading), “gotować” (to cook) → “gotowanie” (cooking). Nearly any verb can get this treatment, which is exactly what let the poet rhyme “mycie” against “krycie” so neatly.