When multiple users on a site adds and updates content, plugins and themes, or changes layout in the customizer, it can get difficult to keep track of who is doing what, and when. Activity Log keeps a log of all actions on the site, and in combination with a scheduled backup and post revisions, it really puts you back in control.
Extract from WordPress.org
Want to monitor and track your site activity? Find out exactly who does what on your WordPress website. The Activity Log plugin is like an aeroplane’s black box that logs every activity in WordPress, and lets you see exactly what people are doing on your site.https://wordpress.org/plugins/aryo-activity-log/