In general, every syllable in a spoken language has a vowel at its core and, In English, may have up to three consonants on either side. So the words a, me, him, and strengths are one-syllable words. Despite varying quite a bit in the presence or absence of consonants, each of these examples has only one vowel.
In spoken English, certain consonants can have vowel-like characteristics. Sounds that are classified as liquids and nasals can function as the core, or nucleus, of a syllable.
Notation
In the International Phonetic Alphabet (IPA) syllabics are shown with the phoneme letter with a syllabic noation line below n̩ m̩ l̩