On every points type edit screen you will see a new meta box where you can configure the conversion rate of this points type.
The conversion rate configured is the value in money that has this points type. If you set a conversion rate of $1 to 100 points, if you set a purchase form to purchase 1000 points, user will need to expend $10 to get them.
Also, you are able to configure a different conversion rate for each points type.
This conversion is used to make all calculations to convert points to money and viceversa on points purchase forms like [gamipress_points_purchase_form] shortcode and GamiPress: Points Purchase Form widget.