Dear Manochitra,
Most probably your question pertains to shops and establishments, I think. Sick leave generally means short spells of leave taken by employees on occasional and ordinary sickness like cold, stomach pain, fever etc., which require a brief medical management. It is thus different from that of medical leave which has a long duration of treatment under constant medical care and supervision. For further details, pl refer to my reply dated 22-11-2016 on the thread " How many day medical leave ".