The spelling of the word "de trains" may appear unusual at first glance, but it is actually a common French expression meaning "of trains." In French, the word "de" connects two nouns and is pronounced as "duh" [də]. The word "trains" is pronounced as "trɛ̃" [trɛ̃], where the nasal "ɛ̃" sound is unique to the French language. Together, "de trains" is pronounced as "duh trɛ̃" [də trɛ̃] and is used to describe anything related to trains.
The term "de trains" does not have a specific etymology as it is not a recognized word in English or any other widely spoken language. It appears to be a combination of the French preposition "de" meaning "of" or "from", and the plural form of the English noun "train", which refers to a set of connected vehicles that move on rails, typically used for transportation. However, the specific context in which you are encountering this term might help provide further clarity.