Refers to a line of people or things arranged one behind another, as opposed to a horizontal row (横列). Common in military, marching, and organizational contexts.
See also: 横列
The soldiers marched in a column.
Please park the cars in a line, one behind the other.
parallel parking
Compound of 縦 (vertical) and 列 (row, line). The reading is on'yomi for both characters.