What does #CA discharge mean?
If the capacity of a battery is 7Ah (amps x hours), 6CA discharge means 6 x 7 x A = 42A discharge. If the battery is 12Ah and the max discharge current is 5CA, the max discharge current will be 5 x 12 x A = 60A.
What are the main specifications of rechargeable (secondary) batteries?
They include capacity (mA x hour), internal resistance(m Ohm), dimension, cycle life(times), maximum charge/discharge current (C), self discharge rate. There are other important specifications, e.g. under / over charge whether it will explode.