And I translate (while fervently hoping I get it right):
The nomenclature (or naming system) of Nokia products is based on distribution per series and levels, thus generating 17 different product categories.
The S series is an exclusive [series comprised] of a limited number of mobile (handsets) [having features] not found in other product series.
The N series [has] phones featuring [greater] innovations and [...] advancements.
The E series concentrates on productivity and business (e.g. push email, [...])
The X series concentrates on entertainment and social networks with a younger target market.
The C series is at the heart of Nokia's product range.
OK, so far we've seen Nokia C1, C2 and its variants, C3, C6, leaked C7, E5, X2, X3, X5, X6 and N8. Please use TP search box above to learn more about these handsets.
*Notice that the number 4 is not used in the product nomenclature as 4 is considered an unlucky number in most cultures.
** Nokia N9 is rumored to be the first Nokia handset to run on MeeGo operating system, a product of a joint venture between Intel and Nokia.