"She is drinking water."
Translation:Ona pije wodę.
"Wodę" is instrumental here? Or accusative? In Russian, "ona pjot wodu [accusative]"
Accusative. Instrumental form for "woda" is "wodą" anyway. Moreover feminine nouns with ending -a are always accusative form with -ę and instrumental form with -ą. I hope it helps you to remember.
The pije word is very similar to hindi word पिये . Both have same pronounciation and meaning.