its on my curve in my email, sms and mms options

If you're referring to the Reconcile Now option, that's for BES. If you open an email on your mailbox it should show opened on your device, if it doesn't happen instantly, you can select that option and it will reconcile your device to mark the items read. That's just a brief example.

thanks. yea, i meant the reconcile now option

so if we don't have BES, and we click it.....what happens? nothing?

Nothing will happen.

As I understand that function, using BIS, when you hit "Reconcile Now", email deleted on the BB will also be deleted on your email server. Generally this is done when RIM polls for email the next cycle after you hit that option.

It does nothing to mail already downloaded to your PC's email client however.

You can get partial reconciliation under BIS in certain circumstances. If that applies to you then Reconcile Now will reconcile whatever it can.