＜Regarding to the "Action" field  in the Versions tab of LEX Knowledge＞

Hi everyone, happy new year to all of you! I have 2 questions as written below. By any chance, if you know how to do it, I'd appreciate it if you would tell me.

【Questions】

１．What kind of value does the "Action" field of the Version tab of Knowledge display?

２．What kind of settings/implementations are necessary to display the value of the "Action" field in 1 above?

I tried to look it up in the help&training(*1), but couldn't find some hint.

In addition, I tried to implement the knowledge action setting in Salesforce, but the  value of "Action" was still left as blank.

Please refer to the screenshot for more details.

(*1) These are the materials I referred to:

・Authoring Actions in Lightning Knowledge

https://help.salesforce.com/articleView?id=knowledge_lightning_authoring.htm&type=5

・When Are Lightning Authoring Actions Available?

https://help.salesforce.com/articleView?id=knowledge_lightning_actions_reference.htm&type=5