Update index.md

docs/en/data_types/special_data_types/index.md

 # Special Data Types {#special-data-types}
 
-Special data type values can’t be saved to a table or output in results, but can be used as the intermediate result when running a query.
+Special data type values can’t be serialized for saving in a table or output in query results, but can be used as an intermediate result during query execution.
 
 [Original article](https://clickhouse.tech/docs/en/data_types/special_data_types/) <!--hide-->