Update time-and-date.md

Co-authored-by: Jason Stirnaman <[email protected]>

Author: MeelahMe

content/shared/sql-reference/functions/time-and-date.md

@@ -885,8 +885,10 @@ LIMIT 1
 
 ## from_unixtime
 
-Converts an integer to RFC3339 timestamp format (`YYYY-MM-DDT00:00:00.000000000Z`).
-Input is parsed as a [Unix nanosecond timestamp](/influxdb/version/reference/glossary/#unix-timestamp)
+Converts an integer (Unix timestamp in seconds) to a timestamp value.
+The underlying result is a timestamp (`Timestamp(TimeUnit::Second, None)`).
+In query results, JSON, CSV, and "pretty" formats render the timestamp as an ISO 8601 string (`YYYY-MM-DDTHH:MM:SS`, without a timezone indicator).
+When output to Parquet, the raw integer value (for example, `1641042000`) is preserved.
 and returns the corresponding timestamp.
 
 ```sql