A column was a military formation used to arrange soldiers on the battlefield.
The Bajoran Militia had their ground troops organized into columns. During the Alliance for Global Unity's coup, General Krim ordered troops to regroup with the 14th Column south of the capital. (DS9: "The Circle") Later, while attempting to evade the Bajoran Militia, Shakaar Edon lead his "rebels" to Tanis Canyon, ordering Kira Nerys on point, with a column of twos behind her, and Lupaza taking up the rear. (DS9: "Shakaar")
During the siege of AR-558, two columns of Jem'Hadar soldiers advanced on the Starfleet position holding the captured Dominion communications array. (DS9: "The Siege of AR-558")