An upright division, in a structure or a table. Both a support that bears load and a field that holds one kind of thing.
Latin columna (a pillar), related to collis (a hill), from a root meaning to rise; a column is, at the root, a thing that stands up.
The two senses share a shape rather than merely a word — a column holding up a roof and a column holding one kind of value both work by standing apart from their neighbors and carrying only their own share, so removing one changes what the whole can bear without touching any other column at all.