At home, at school, at work
'पर par usually means 'on', but it means 'at' in phrases like 'घर परpar 'at home'.
आज मनोज घर पर नहीं है .
aj Manoj ghar par nahin hai. Manoj isn't at home today.
राम स्कुल पर नहीं है .
Ram skia par nahin hai. Ram isn't at school.