The Sector/Group option allows you to select certain Sectors or Groups to scan for in the Trade Seeker.
A Sector is comprised of a group of companies that generate income in similar ways. All companies in the Services Sector provide some kind of service as their main revenue.
A Group or Industry is a list of companies that are in the same line of business. Such as the Services Sector is comprised of the Groups Printing, Hotels, and Restaurants.