Syllabification is the process of dividing words into syllables for pronunciation. The number of syllables per word is equal to the number of vowel sounds in the word! With this definition, it is important to keep in mind that the diphthong, although comprised of two vowels, generates a single vowel sound.

A syllable is that part of a word which has only one vowel sound. Words can be divided into their component syllables.
e.g.:-
    --- think - single syllabled word.

    --- pro-ject - 2 syllable.

    --- con- si-der - 3 syllable. etc.

Each line of a sonnet is said to have exactly 10 syllable.