A character’s Movement Budget is determined by their highest Speed (usually base speed). During their Turn a character can move a total number of meters up to their Movement Budget. This movement can take place at any point during a character’s Turn, either before or after any actions they take.
Example
A character’s Base Speed is 13m and their Climb Speed is 7m, so their Movement Budget is 13m. They make a standard move for 8m, so they can only climb for 5 meters with their remaining Maximum Movement unless they use a Dash action.