What is an "In-App Purchase, ie Babbel? Is there a charge for this?

An In-App Purchase is just that...a purchase (using money of course) you make from within the app such as "gems", levels (games mostly), removal of ads, etc. Most times the app itself is free...to enhance the app costs real $. To see the actual In-App Purchases, view the app in the App Store and scroll down to the In-App Purchases section to find the features and their respective cost.

An in-app-purchase is just that, a purchase made while using an app. For example, I have a puzzle game on my iPad. It offers various amounts of hints to help solve a puzzle. I can buy a hint package while using that app. The fee is deducted from my iTunes account. I use iTunes cards for all of my purchases.