How to find cycle count in big sure??and what is this number about??

Apple menu > About this Mac > System Report > Power.

A battery cycle is one full charge, or two charges from 50% to 100%, or one charge from 50% to 100% plus two charges from 75% to 100%, or any other combination of charges that equal one full charge.

Old Toad wrote:

...A very good app (which is free) to check on the condition of a devices battery is CoconutButter. ...

I think you may be fantasizing about getting a sun tan on a tropical island in February? More fun than Coconut Battery!

No. This is what I found via a Goole search;

About battery cycles

A charge cycle happens when you use all of the battery'spower—but that doesn't necessarily mean a single charge. For example, you could use half of your notebook's charge in one day, and then recharge it fully. If you did the same thing the next day, it would count as one charge cycle, not two.

That's the number of re-charges your battery has undergone. A very good app (which is free) to check on the condition of a devices battery is CoconutButter. Here's what it can tell about an iPhone:

Now there's a Freudian slip big time!

Yes, it will still increase. To maintain low battery cycles: when near an AC outlet, leave it connected to the charge circuit. If you need portability, use it on battery power.