As long there are no reallocated sectors the drive may still be fine (your current data certainly has some damage, you better have a backup here.) Basically a "uncorrectable" is a sector that can't be read anymore for various reason.… aka the data is bad currently. It does not automatically mean the sector/disk structure itself is broken.
The proper operation in this case is to full wipe the drive with a proper format (zero fill). Don't do a quick format! Only afterwards you will know for sure the drive is bust or not. In case there's permanent damaged sectors those "pending" ones would convert to "reallocated" sectors. If there was just some bad data the "pending" ones simply will disappear. If your disk collects reallocated sectors then it's probably time to look for a new disk (albeit a low count of reallocated sectors that stays stable isn't the end of the world either).