Your character's Movement Points determine his potential of movement. Moving a fighter takes away Movement Points from his MP capital. Set to 3 MPs for all the fighters, this number can either be increased or reduced with spells and/or equipments.
Special case: When a fighter is on one of the four adjoining squares of the one where the creature or another fighter is, he is said to be in a tackle area (also called control or tackle area). The possibility to dodge and therefore to escape from the tackle area depends on the agility of both fighters. Indeed, the bigger the gap between the agility scores, the higher the chance of the fighter to get out of the tackle area. If you fail, you miss both your dodge and turn. Each time you move, it costs you between 1 and 3 MPs, depending on the number of squares you used to move.

May the cleverness be with you! Some creatures have more than 3 MPs and 6 APs! Some rare equipment will enable you to increase your AP and MP number.