A “translation” is counted when a single non-English review is translated to English.
You can choose which apps to enable translations on from the Manage Sources page in your account.
If translations are enabled for an app all non-English reviews will automatically be translated to English, until you’ve used up the translations included on your Appbot subscription.
Different subscriptions include different volumes of translations – see the Plans page for full details. Extra translations can be purchased for a small extra cost by contacting firstname.lastname@example.org.