Move the figures from one province to empty villages in a different province.
When you order your troops to March, you must pay 1 Rage. Choose one province (you cannot choose a fjord) and move any number of your figures from that province to empty villages in another single province. The destination province doesn’t have to be adjacent, it can be anywhere on the board.
You cannot move figures from two different provinces in the same action, nor move your figures to two different provinces. You can only March from any one province to any other.
Using the March action is generally the only way to get your figures to Yggdrasil. There are no villages in Yggdrasil, so there is no limit to the number of figures you can have there.