Another word for economic activities is JOBS. There are three main types of economic activities.
3. Tertiary (Services)
These were the first ever jobs. They work with the products from the land and the sea. E.g. Farmers, Fishermen, Forestry and mining.
This sector is where people manufacture products (Mostly in factories)
Any job that provides a service is in the tertiary sector. E.g. Teachers, Doctors, Taxi Drivers etc.