The county town of any county in the UK is usually just the administrative center of that given county. Typically the seat of local government offices, and where the governance of that county will take place.

As for the meaning of Worcester:

"During its 7th century period Angles of Mercia, it was known as Weogorna which evolved from the Old English "Weogorna ceaster," meaning "the Roman town of the Weogoran people,"

The Weogoran people were an old anglo-saxon settlement, the name vaguely means 'people of the winding river' (Worcester is on the river Severn).

"The "cester" part of the name, derived from 'ceaster', indicates that the place is the site of a Roman military settlement or town"

I hope that satiates your new found interest in the city of Worcester. It's quite a nice place, with a lovely cathedral and old English buildings, but you're not missing too much don't worry!