ArabicMeaning or significance
إِنَّمَاrestriction and emphasis
الْأَعْمَالُdeeds; singular عَمَل
بِالنِّيَّاتِaccording to intentions; singular نِيَّة
لِامْرِئٍfor a person / each person's share
مَا نَوَىwhat that person intended; نَوَى is a past-tense verb
إِنَّمَا الْأَعْمَالُ بِالنِّيَّاتِ establishes the central role of intention in the religious standing and reward of an action. وَإِنَّمَا لِامْرِئٍ مَا نَوَى relates the outcome to the individual's actual purpose.
Niyyah means the purpose and resolve of the heart. Merely repeating a verbal formula is not a substitute for that resolve; nor does a good-sounding aim turn a prohibited act into a permissible one.