Many people ask me if I know sign language. I said: Not during the day. Only at night, three two, five one, plus one, open! What does this mean?

This sentence is meant as a joke. It means that when he goes to the bar at night, he often needs to use his hands to make gestures.

The following is a relevant introduction to sign language:

Sign language (C) uses gestures to compare movements, and simulates images or syllables according to changes in gestures to form a certain meaning or word. It is It is a hand language used by people who are hearing impaired or unable to speak to communicate with each other and exchange ideas. It is an "important auxiliary tool for audio language", and for people with hearing impairment, it is the main communication tool.

The difference between sign language and language mainly lies in the issue of pronunciation and whether deaf-mute people think with gestures.

On July 1, 2018, China implemented the "National Common Sign Language Vocabulary List" and the "National Universal Braille Program" and released them as language and writing specifications. On March 1, 2021, the State Language Commission's language and writing standards "National Common Sign Language Plan for "National Anthem of the People's Republic of China" (GF0024-2020) was officially implemented.

The above information refers to Baidu Encyclopedia - Sign Language