The key concept to take away here is that Newlands began to see similarities in physical properties having atomic weights close in range that came with groups of 8. So, the rows show the groupings based on relatively close atomic weights (designated by color). But, he also noted similarities in reactive, or chemical properties. So for these elements, he stacked these elements to form columns (designated by font), to denote that the element forms a second grouping, aside from the rows which assigned it to a first grouping.
Each element is now categorized in 2 ways: a row, or Periodic, grouping, and a column, or Group, grouping. Herein lies the foundation of the Periodic Table!