I haven't a clue what this means.
There are lots of low-skilled and high skill jobs that go wanting. Construction and agriculture are greatly hampered by the lack of workers. Depending on one's biases, one could call these jobs "skilled" or "unskilled".
Obviously there are hundreds of thousands of tech jobs that cannot be filled. The companies are forced to have much of their work done overseas.
As an aside, a healthy economy NEEDS young workers. In order to avoid the problems of an aging population, we need to either greatly increase the US birth rate or have more immigration. With regard to skills, we have solved this problem for hundreds of years. The first generation has much less education (what you might mean by skill) than their children and grandchildren. Having said this, the skill levels of African and Asia workers in very high indeed. So, the first generation might fill the menial jobs that Americans have no interest in filling. Their children will be college graduates at the same level as non-immigrant families.
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Finally, we MIGHT try to address the reason that so many Americans are not working [the labor participation rate is low]. One of the main issues is drug use (these folks cannot pass a drug test) and the lack of vocational training.