Grammar Monster does a great job of describing Consonants here: https://www.grammar-monster.com/glossary/consonant.htm
“A consonant is a letter of the alphabet that represents a basic speech sound produced by obstructing the breath in the vocal tract. All the letters in the alphabet apart from A, E, I, O, and U (called vowels) are known as consonants.
For example:
- T is pronounced using the tongue (front part)
- K is pronounced using the tongue (back part)
- B is pronounced with the lips
- H is pronounced in the throat
- F is pronounced by forcing air through a narrow gap
- M is pronounced using the nasal passage
A consonant can be combined with a vowel to form a syllable.”