You have to enable Unity Purchasing as following steps via link https://docs.unity3d.com/Manual/UnityIAPSettingUp.html
You have to enable Unity Advertisements as following steps via link https://unity3d.com/services/ads/quick-start-guide
Add Monetization Manager component to any game object, you can set Unity Advertisement configs, IAP products, Virtual currencies here
You can create In-Game product data by right click on project tab, Choose Create -> Monetization -> In Game Product, you can extends this class (InGameProductData) to make in game items with stats
You can create IAP product data by right click on project tab, Choose Create -> Monetization -> IAP Product. In IAP product you can set title, description and price by managable IAP catalog, You can learn how to manage catalog here https://docs.unity3d.com/Manual/UnityIAPCodelessIAP.html. Moreover you can add amount of virtual currencies, in game products