“Lucy is really on the ball, she already finished all her essays for this term.”
“Samsung is really on the ball with their new smartphone, it addresses user needs perfectly.”
“On the ball” is an idiom with a positive meaning. It means that someone is competent and attentive, able to do a good job because of their focus. It can also mean that someone is knowledgeable and alert, able to pay attention to new trends and ideas.
The origin is believed to be from sports. Coaches would tell players “Keep your eye on the ball” telling them to look at and pay attention to the ball, and not get distracted. We use it now for people that exhibit good focus or for people that are successful in something because of competent actions.
“Lucy is really on the ball, she already finished all her essays for this term.” = Lucy has used her focus and hard work to be successful in completing her work quickly.
“Samsung is really on the ball, with their new smartphone, it addresses user needs perfectly.” = The Samsung company is really aware of current trends and needs, and uses that knowledge to make a successful smartphone.