looking to buy a zippy flight max lipo 2s 1300ma 15-25c

that means 15c(19.5amp) continuous
and 25c(32.5) burst

what is this burst rate?
how does we attain burst rate
what esc specification for this,which current rating should choose

See the rchelicopterfun.com link in this post :

http://www.rcindia.org/batteries-and-chargers/introduction-video-for-lipo-batteries/msg3146/#msg3146

It is basically support for short periods ("burst"s) of high discharge over and above their "continuous" C rating.

ESC selection is driven by motor and prop selection as the current needed comes from this.  Once you know the motor/prop amps draw, you pick the ESC, and based on ESC selection you choose the battery.

The burst rate is the current that can be drawn from the battery for a few seconds.. i.e. you may draw 25c from the battery for a few seconds before you start damaging it.. But while selecting the battery, you should go by the continuous rated current not the burst current..