Planes are divided into various classes of seats - economy class, business class and first class seats. Smaller planes only have economy class seats, whilst a common configuration for larger planes is to have a combination of economy and business class seats. First class seats are less common than they once were.
First class seats are the most luxurious seats on a plane, whilst economy class (colloquially known as "cattle class" but also know as "Voyageur" on Air France flights) are the least comfortable seats. Often there are curtains on a plane which seperate the various classes. In line with first class seats being the most luxurious they are also the most expensive. First class seats are usually located near the front of a plane, allowing the first class passengers to disembark first.
Air France refers to its first class seats as "Première".