Propene. what does the name of this hydrocarbon tell you about its molecular structure?

This name tells us that the molecule has three carbons and has a double bond in it.
pro means three carbons when talking about hydrocarbons
ene means the presence of at least 1 double bond

ane means all single bonds and yne means at least one triple bond which means that propane is a three carbon molecule with only single bonds connecting them while propyne has three carbons with a triple bond between 2 of the carbons.

I hope this helps.  Let me know if anything is unclear.