This is discussed most frequently regarding vintage Rolex, and the below descriptions are based on this context.
Matte dials are not shiny, and have a “flat” utilitarian (at least to me) appearance. The process to create this dial is straightforward: plate is printed, then text, logo, and so on, are applied.
Glossy dials are those that have been coated with a lacquer, and appear shiny, most notably when viewed in the sun at an angle. Text may be under or on top of the lacquer.
Some collectors refer to dials as gilt solely based upon the gold (most often) print color. In the context of vintage Rolex I personally think for clarity these should be called gilt print.
I would use the term gilt dials to describe only those produced with a portion of the underlying metal plate exposed. That exposed plate is most often gold in color (brass), but it is not a requirement – it could be any material color which has been applied to the plate. The plate then coated, and as a result, when the black paint is applied, it does not adhere to coated portions. These coated portions are often are the manufacturer logo, name and other text, and the process leaves those printed in negative relief as gold, and the rest of the dial black. The exposed portions therefore sit slightly below the black paint on the dial. In this state the dial can be referred to as “gilt”. The dial may or may not then have a lacquer finish, which if added will provide a shiny appearance and then referred to as gilt-glossy. Whether or not a lacquer is applied, additional text may be added.