Explanation/Reference:
When you delete an item from a SharePoint document library or list, it isn't immediately removed from SharePoint. Deleted items go into the site recycle bin for a period of time. During that time, you can restore the items you deleted to their original location.
Restore items from the SharePoint 2016 or 2013 Recycle Bins
1. Click Recycle Bin in the Quick Launch bar on the left of the screen.

2. On the Recycle Bin page, click the box to the left of the items or files to select the ones you want to delete or restore.
3. Click Restore Selection to recover the selected files.
References:
https://support.office.com/en-us/article/restore-items-in-the-recycle-bin-of-a-sharepoint-site-6df466b6-55f2-
4898-8d6e-c0dff851a0be