The size of the map in Assassin's Creed Valhalla would turn travelling without fast travel into quite a nuisance. Luckily, there is a fast travel system in the game, and on this page, you will learn how to use it.
How to unlock a fast travel option?
The basic points of fast travel are those marked on the map with the raven icon. At first, fast travel to such places is impossible, but if you get to the top of such a point it will be permanently revealed - you will be able to go to the place at any time ("capturing" such points also enables you to discover valuable items and secrets). All you have to do is open the map, select a previously explored point, and use the fast travel option.
Fast travel (and map synchronization) points are easy to recognize - they are high rocks that will be marked on your compass if you are near them. Remember to reveal sch points every time you see them - they will help you to explore the world.
Other points to which you can travel are the discovered settlements and towns. All you need to do is to reach such a place once, and it will always have an option to fast travel on the map.