Every syllable in Hebrew will begin with a consonant and will include one full vowel. It may contain one full vowel and one-half vowel, but never less than one full vowel, nor more than one full and one-half vowel.

There are, strictly speaking, two kinds of syllables: open syllables and closed syllables.

The simple closed syllable is a syllable that ends in a consonant that is not doubled. A closed syllable must have a short vowel in it unless accented. If the syllable is accented, it may take a long vowel; however, it does not have to change to a long vowel. Note that every simple closed syllable ends in a syllable divider except when the syllable is the final syllable. Examples: הַכְבֵּד הַר עַל אֶל

The sharpened closed syllable is a closed syllable that ends in a double consonant. This syllable likewise must have a short vowel unless it is accented. הַקּוֹל כַּבֵּד
Note: Consonants are not written twice together in a word but are doubled by means of a dot in the center of any letter (except the gutturals), which is called the daghesh forte.
Example: קִטֵּל kĭt-tēl, מַשֵּׁל mĭsh-shēl, הַקֹּוֹל hăk-kôl. Every time there is a doubled letter, a sharpened closed syllable precedes it.
The two letters ה and ח may be doubled by implication. Where a doubling should occur, these letters do not take the daghesh forte written but are considered and treated as if it was there. One cannot pronounce ה or a doubled ה differently. Example: הַהוּא ,הַה֣שֶׁךְ. The ח is doubled by implication, thus the first syllable of the word is a sharpened closed syllable.

A half-closed syllable is a syllable that ends in a consonant supported by a vocal shewa. This syllable has a short vowel unless accented. In pronunciation, it is impossible to determine whether the consonant with the vocal shewa closes the first syllable or opens the following syllable.
Example: קָטְ/לוּ קָ/טַלְתְּ עִבְ/דוּ
Thus, the half-closed syllable is a closed syllable that has been half-opened again by virtue of the composition of the vowels or of the inflection of the word. Example: עִבְ/דוּ. The first syllable is a half-closed syllable. It is a closed syllable; yet it ends in a vocal shewa. Since the shewa is the result of volatilization (changing of forms), it has not lost its original vocalic (vowel) value and leaves the syllable not fully shut, “half-closed”.
When a syllable ends in a shewa, it will be difficult to determine accurately whether the shewa is a vocal shewa or a syllable divider. If there is a daghesh in the consonant immediately following the shewa, that shewa is always a syllable divider. A daghesh forte cannot follow a vocal shewa or a syllable divider. Only תּ פּ כּ דּ גּ בּ can ever receive a daghesh lene.
Also, if the full vowel preceding the shewa is marked by a metheg (֣), the shewa is distinguishable as a vocal shewa.

If a shewa is beneath the initial letter. Example: בְּרִית

If two shewas (one will be silent and the succeeding one will be vocal) come consecutively, the dividing mark will come between the two consonants under which the shewas occurs. Example: נִקְ/טְלוּ

If a shewa occurs beneath a letter that contains a daghesh forte, the dividing mark will occur between the two consonants. Example: קִטְּ/לוּ