code: public function table_column( $content, $column, $user_id ) {
  
  		if ( $this->column_name !== $column )
  			return $content;
  
  		// Unicode checkmark u2713: ✓
  		$check = "\xe2\x9c\x93";
  		// Unicode ballot X u2717: ✗
  		$ballot_x = "\xe2\x9c\x97";
  
  		$user_settings    = apply_filters( 'iac_get_user_settings', array(), $user_id );
  		$subscribe_status = function( $type ) use ( $user_settings, $check, $ballot_x ) {
  			$key = "inform_about_{$type}s";
  			if ( ! isset( $user_settings[ $key ] ) ) {
  				return $ballot_x;
  			}
  
  			return $user_settings[ $key ]
  				? $check
  				: $ballot_x;
  		};
  
  		$posts    = $subscribe_status( 'post' );
  		$comments = $subscribe_status( 'comment' );
  		$cell     =
  			  __( 'Posts', 'inform_about_content' ) . ": $posts<br/>"
  			. __( 'Comments', 'inform_about_content' ) . ": $comments";
  
  		return $cell;
  	}
docs: @wp-hook manage_users_custom_column
  
  @param string $content
  @param string $column
  @param int    $user_id
  
  @return string