What does FH, FM, VM and FMX mean?

XH

The XH comes from extra heavy, that is, a brute that pulls a lot! An extra heavy.

N10

Older models referred to engine liters in the name. The N10, with a 10-liter engine, follows this logic. The N, on the other hand, comes from the English word nose, which can be translated as nose and refers to the pointy design.

NL

Following the same pattern, this Volvo uses the N for being a pointy and the L is related to the wider cabin that allows to increase the bed.

FH

Models with F in the name refer to Frontal, straight front, the famous flat face. The H, on the other hand, refers to High which in English means high, or in this case, high cabin.

FH16

Now it's easy, right? Flat-faced, the FH16 earns the two numbers in the name in reference to the engine volume of 16 liters.

Full story at https://www.volvotrucks.com.br/pt-br/news/blog/institucional/significado-nomes-dos-caminhoes.html