Aikido originated from the sword techniques of the Japanese Samurai. It unites the speed and graceful effectiveness of their techniques with the inner peace of Zen meditation.
One part of the training is to move in such a way that you evade the attack and unbalance the attacker. Followed by a throwing technique or a lock on joints that can be quite painful for the attacker but do no damage. In that process you also learn to roll by using the energy of falling to stand up.
Some other developmental goals are:
Learning to maintain your own space, both physically and mentally, without hindering or damaging others.
Stepping out of easily escalating patterns of attack and defense.
Neutralizing an attack from a situation of peace, overview and self-confidence.
Not getting stuck in a conflict by projecting your energy beyond the obstacle or conflict. Being aware of the conflict and trying to resolve this without getting stuck in it by fixating your attention on what separates you from your opponent
Learn to stand, sit and move with a relaxed strength that comes from your whole body instead of, for instance, only from the muscles of arms or legs.
Strengthening your inner life force and health. Strengthening your lungs and using your full lung capacity by learning to breathe deeply.
All this improves your physical and mental flexibility, stability and resistance.