What will happen if I will copy the information from encrypted hard drive? Will it be store decrypted? I have encrypted my hard drive with FileVault.

If I will manually create a backup by copying to some external hard drive - how will the information on this external one be stored?
It will be stored as plain files; FileVault encryption only protects files when thy're on your startup volume. You can encrypt the external drive if you want. You can also create an encrypted disk image, store the image on the external disk, and then store files inside the encrypted image. But unless you do something to encrypt the files, they'll be freely readable from the external disk.

BTW, the same is true of Apple's Time Machine backup system -- backing up a FileVault-protected Mac results in an unencrypted backup unless you choose the option to encrypt the backup.