A lightning action is a type of quick action that can invoke a Lightning component, a Visualforce page, or a URL. The administrator can use a lightning action to redirect the user to a different page after they finish the screen flow. This way, the user will not see the initial screen again and will not misuse the flow tool.
Reference:
https://help.salesforce.com/s/articleView?id=sf.lightning_component_actions.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.flow_distribute_lex.htm&type=5