Thank you Tim for your help.
The content item cannot be opened, because it is being edited by another user.
When a content item/page is edited by another user, in the list of content items/pages, the system displays
next to the item.
More information about types of statuses could be found here
the Telerik team
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items