First of all a linocut is a printmaking technique, very similar to a woodcut, in which a sheet of linoleum or a linoleum block is used. A design is carved into the linoleum surface with a sharp knife. In a reduction print the artist prints all colors from the same block. For each color pass through the printing press the artist removes more material from the block. A reduction print can therefore never be reprinted. Each color is printed on top of the previous. The artist must print the entire edition as the work is done, because the printable area of the single block is reduced with each pass.
Here is an example of a reduction print of a star I did a couple of years ago. The paper passed through the press five times to reach its final completed state.