In a game of diplomacy, such as Victoria games, relations between countries are kind of a big deal. Developers are taking a page from other Paradox titles, and adding a twist of their own.
Starting out with Relations, this is a value on a scale between -100 and +100 that determines the overall diplomatic standing between two countries, similar to relations/opinion in games such as Europa Universalis and Stellaris.
The key difference between Relations here and in those games is that in Victoria 3 relations are bilateral, meaning that while in Europa Universalis France can have a relation of -100 with Prussia while Prussia has a relation of +100 with France, in Victoria 3 these two countries will always have the same Relations score towards each other.
So, how do you raise and lower relations? The primary way is through the Improve Relations and Damage Relations ongoing diplomatic actions, but there are many other ways in which relations can be increased or decreased, including various events, Diplomatic Incidents, and the Expel Diplomats diplomatic action, which is a way in which one country can act to prevent another from cozying up to them relations-wise, though at the cost of gaining Infamy.
All of these have an impact on the AI’s decision-making in terms of which diplomatic proposals it will accept, which side it will want to join in diplomatic plays, and so on, but besides that, there are also limitations on what actions you can take against another country based on your mutual Relations.