This package gives you 1,200 Gems in total. The +20% bonus is already included in that 1,200 - you will not receive 1,200 Gems and then an extra 20% on top.
What You Get
1,200 Gems in total, added straight to your account
That total is made up of 1,000 base Gems + 200 bonus Gems (the +20% bonus)