Functional movement refers to movements commonly performed in everyday situations.
The idea of functional exercise focuses less on using extensive machinery such as bench press or leg extension commonly available in most fitness facilities but more on their functional counterparts such as pushups and squats.
The idea of functional exercise has become more prevalent in sports training as well. You now would rarely see high performing athletes doing excessive weight training, the shift has been made to focus more on the exact movements and types of movements performed during the sporting activity. Training specificity has been one of the more prevalent ideas in the world of physiotherapy and athletic therapy for a while.
Sports requiring speed and agility should focus on movements that emphasize speed and agility. If you are a basketball player you will have little benefit from squatting 300lbs, However doing explosive sprinting and jumping might be a better training option.
Physiotherapy focuses on regaining functional everyday movement such as squatting. Many people are hesitant to perform squats if they have hip or knee pain. However squatting is one of the most frequently performed movements we do on a daily basis. Without the ability to squat we would not be able to sit in a chair or a sofa, get in or out of bed, or sit down on the toilet.