The "this" in the sentence can be referred to the second division in meiosis.
In meiosis, the process is actually very similar to mitosis, the cell division that leads to genetically identical daughter cells. Except for the fact that meiosis includes 2 times of cell division, leading to 4 daughter cells.
In the first division, the parent cell also duplicates its chromosomes before the division, same as mitosis. However, after the first cell division, the 2 daughter cells divide again but without duplicating it's chromosomes, leading to the genetically non identical daughter cells of meiosis, where number of chromosomes are halved.
Therefore, if the second division of meiosis didn't occur, daughter cells would have two complete sets of chromosomes.
