What does A Wisconsin superintendent justified a plan
to create single-sex high school science
classes based on “research data” showing that
boys like “creative hands-on projects that
culminate in something with a different level
of understanding, mean?

See a translation

It means boys like to learn by doing things using their hands, not by reading about science in a book. Usually, when people say someone likes to learn hands-on or by working with their hands, it means they don't want to read about theory, instead they want to do practical things. Many students like this traditionally have learned trades throught apprenticeships (mechanic, construction worker, electrician, etc.) as opposed to more learning academic fields (chemistry, physics, biology, etc.) So he is proposing to make science education less theoretical and academic and make it more appealing to students who don't learn so well with typical academic methods.