There are 7 ‘short vowel’ sounds, although children are usually only introduced to the 5 which are most commonly heard in simple CVC (consonant, vowel, consonant) words: /a,(æ)/ in cat, /e,(e)/ in peg, /i,(I)/ in pin, /o,(ɒ)/ in hot, /u,(ʌ)/ in bus.
The other two ‘short vowel’ sounds are: /oo(u),(Ʊ)/ in bull or could and /uh,(ǝ or schwa)/ heard as the final sound in the words: zebra, doctor and corner.
Our ‘Short Vowel’ Finger Chant can help you, and your child, to learn and remember the 7 ‘short vowel’ sounds: https://www.teachphonics.co.uk/free-resources-phonics.html