Updated At functions similarly as Created At, except that it provides you with the exact date and time someone edited an item in your board.
When adding this attribute, all you'll have to do is give it a name, and then click Save. It will immediately appear in your item modal/sidebar, with the date and time the item you're viewing was edited.
With this attribute in place, you'll be able to keep an eye on edits and changes made by your team member or collaborator. The date and time will change every time someone edits the item in question.
{primary} NOTE: Just like the Created At/By attributes, Updated At is a static attribute, as well. This means that you can't change its value on your own.