Source

File: wp-admin/includes/class-wp-terms-list-table.php

public function get_columns() {
		$columns = array(
			'cb'          => '<input type="checkbox" />',
			'name'        => _x( 'Name', 'term name' ),
			'description' => __( 'Description' ),
			'slug'        => __( 'Slug' ),
		);

		if ( 'link_category' === $this->screen->taxonomy ) {
			$columns['links'] = __( 'Links' );
		} else {
			$columns['posts'] = _x( 'Count', 'Number/count of items' );
		}

		return $columns;
	}