UTC+00:20 is an identifier for a time offset from UTC of +00:20.
UTC+00:20 was used in the Netherlands from 1 May 1909 to 16 May 1940. It was known as Amsterdam Time or Dutch Time.
The exact timezone was in fact GMT +0h 19m 32.13s until March 17, 1937, when it was simplified to GMT +0h 20m. When Germany occupied the Netherlands in World War II, Berlin Time was adopted, and this has been retained ever since.