いや、質問者、回答者両方ともラベルが低いんでしょ。manに書いてあるのに…

COLUMNS
If this variable contains a string representing a decimal
integer, it is used as the column position width for dis-
playing multiple-text-column output. The ls utility cal-
culates how many pathname text columns to display based
on the width provided. (See -C and -x.)