In Metaphase of Mitosis, the chromosomes line up along the middle of the dividing cells.
Mitosis has four phases which are: Prophase, Metaphase, Anaphase and Telophase. In Prophase, DNA becomes wound very tightly and you can see them. Spindles get formed in this phase.
In Metaphase, the chromosomes line up in the middle (we can say that on the equator) of the cell. Afterward, the two sister chromatids of each chromosome get separated from each other in Anaphase, which results in two sets of identical chromosomes. Here, the arrangement of chromosomes that lined up in the middle, is called Metaphase plate.
And in Telophase, a nuclear envelope forms around the chromosomes in both cells.