Typically omega-3 and omega-6 allow the proper functioning of the cardiovascular, cerebral, inflammatory, hormonal, etc. systems. Also, each of its families of fatty acids have properties, for example omega-3s are good allies for reducing the level of triglycerides in the blood.
Omega 3s increase the ability to use fat as energy. Clearly, they allow you to use your fat as a source of energy, and thus limit its development, for the benefit of the muscle, in order to avoid the catabolic phase in particular.
They allow the body better muscle recovery, we speak precisely of anti-catabolic action. Omega 3s act directly on aches by limiting the sensations of pain. Less trouble recovering from exercise, especially weight training, means better recovery and therefore better future performance.