* "ex" - The "e" in this syllable is a schwa sound, represented by the symbol /ə/. It's a short, unstressed vowel sound.
* "cel" - The "e" in this syllable is also a schwa sound /ə/.
* "lent" - The "e" in this syllable is again a schwa sound /ə/.
So, there are three schwa vowels in "excellent".