Problems with a Workflow for Recruitment with simple approval
Showing your flow is great, but you also need to share the configuration of the action that is causing the error. The only thing I can tell you is that there is a problem with field_6 in the e-mail you are trying to send.
Some people may disagree, but I would recommend that you leave the original name of the actions and append your description after the original name. While you've done a good job with the descriptions, leaving the original action name allows us to see the exact action you used without having to guess which one it is. Without the action name, all of the SharePoint actions look mostly the same. It will also make it easier for you to know what action it is if you need to edit the flow in six months.