"Does it mean that when i read the counter values from RTC ,i should set the bit to 1 ??
"

No it doesnt mean that. WHen you attempt a read, the buffering happens at the internal hardware level to avoid a read when the register is just changing. So you dont have to set or clear bit 6 for a read.

The purpose of this bit 6 would be to halt the count AND save the last count as agaisnt the bit 7 which also halts the count BUT resets the divider. Thus bit 7 will be set when you or the user is updating the current time of the RTC.

Trust its clear.

Raghu