The biceps and triceps muscles work together to allow you to bend and straighten your elbow. When you want to bend your elbow, your biceps muscle contracts (Figure below), and, at the same time, the triceps muscle relaxes. The biceps is the flexor, and the triceps is the extensor of your elbow joint.
Functional means it is in good condition and can perform well. Non-functional tools and equipment means that they are in good condition and can perform its regular functions. Non functional means cannot be used due to damage or defective and needs to be repaired.
