Here's a breakdown:

* C: Carbon

* H: Hydrogen

The formula indicates that butene has four carbon atoms and six hydrogen atoms.

Important Note: The formula you provided doesn't specify which isomer of butene it is. There are two possible isomers of butene:

* 1-butene: The double bond is between the first and second carbon atoms.

* 2-butene: The double bond is between the second and third carbon atoms.

To be more precise, you'd need to specify which isomer you are referring to.