A skilled worker is any worker who has special skill, training, knowledge, and (usually acquired) ability in their work. A skilled worker may have attended a college, university or technical school. Or, a skilled worker may have learned their skills on the job. Examples of skilled labor include software development, paramedics, police officers, physicians, crane operators, painters, plumbers, craftsmen, and accountants. These workers can be either blue-collar or white-collar workers, with varied levels of training or education. (form Wikipedia).
Many times, we talk about skilled workers like the people that has an education where they combine the practical skills with the theoretical skills. In many countries, that education leads to a certificate. That can be like a Journeyman´s certificate. If a person has that kind of certificate, you will know something about his skills and you will trust that his skills can solve the challenges you have. If you have problem with the water tubes, you call a plumber. If you will build a house, you call a bricklayer or a carpenter.
We need skilled workers. We need them to be sure to get quality work done.
It is a long way to become a skilled worker. In many countries, the education for a skilled worker is four years or more. Some places you start the education after lower secondary. Other places you have to complete upper secondary before you can start on the technical or vocational school.