Soccer is a demanding sport that requires both endurance and sprint ability, and those high-intensity efforts result in a high-energy demand.
Especially during periods with many matches or a lot of training, nutrition is important to recover and protect against overuse injuries.
A good diet and the right nutrition can support intensive training while limiting the risks of illness or injury and are also important in the preparation for games and speeding up recovery afterwards.
Here's a great guide for ensuring player recover.