Pending sectors are ones, that for some reason drive could not read previously. They get resolved by overwriting. Then depending on success of overwrite operation they either are considered fine or get relocated.
Resolving of Pending sectors can be done with mhdd (scan with relocate) and with victoria.
MHDD is the most popular freeware program for low-level IDE, Serial ATA and SCSI HDD diagnostics.
hddguru.com
https://hdd.by/wp-content/cache/all/victoria/index.html
Raw Read Error Rate a critical SMART parameter that indicates problem with the disk surface (platter that stores the data), the actuator arm, and the read/write head. A higher RAW Read Error Rate indicates higher chances of disk failure.
On different drives this parameter works differently. For example on Seagate drives it's quite normal to have high Raw Read Error Rate. On WD drives Raw Read Error Rate should be zero.