skilled and experienced in a particular area

कुशल

English Usage: She is proficient in playing the piano.

Hindi Usage: वह पियानो बजाने में कुशल है।

the state of being proficient; a high degree of competence or skill

दक्षता

English Usage: Her proficiency in multiple languages is impressive.

Hindi Usage: उसकी कई भाषाओं में दक्षता अद्भुत है।