Skeletal muscles are joined to bones by tendons, which are composed of tough connective tissues. When a muscle contracts, the tendon pulls on the bones and makes them work like a lever does. Muscles provide the force to move the lever. Places where bone meets bone are called joints. They work as a fulcrum which is a point around which the lever works. An example is the elbow joint. If you wish to see the action of a tendon, a chicken wing is a good example. You can use a tweezer to pull on the tendon and observe how that affects the bones in the chicken wing.
Tendons are the hard felxible fibrous connective tissues that basically attaches muscles to the bones and muscles to structure such as eye balls, making the bone or structure move easily.
The role of tendons in the skeletal and muscular system is that tendon basically joins bones and muscles together in order to support the movement of the muscle, that is when the muscle contracts the tendons makes the bone move in the direction the muscles wants, while acting like a lever.