Video Description:

The Witcher 3 Wild Hunt - Power Overwhelming - Have all possible Place of Power bonuses active at the same time. [Bronze / 15G]

Places of Power are ritual stones hidden in the woods of the White Orchard Map (that's where the game starts). They are marked with question marks on the map until you have discovered them. Activating the places of power will earn you a skill point and give you a significant boost for one of your signs. You have 5 signs, so you need to activate the 5 corresponding stones. One for each sign.
The catch is that the effect only stays active for 30 minutes. That means you have to activate all stones in quick succession. But no worries, there's more than enough time and you can make use of fast travel if you wish.