* "pen": The vowel sound is a short "e" sound, similar to the "e" in "bed" or "get."
* "nies": This is a bit trickier. It's a combination of a short "i" sound like in "pin" and a schwa sound (the "uh" sound in words like "about").
So, the vowel sounds in "pennies" are:
* Short "e"
* Short "i"
* Schwa