ad - jec - ti - val
There are many reasons to learn how to divide adjectival into syllables. Separating a word like adjectival into syllables is mainly to make it easier to read and pronounce. The syllable is the smallest sound unit in a word, and the separation of the adjectival into syllables allows speakers to better segment and emphasize each sound unit.
Knowing how to separate adjectival into syllables can be especially useful for those learning to read and write, because it helps them understand and pronounce adjectival more accurately. Furthermore, separating adjectival into syllables can also be useful in teaching grammar and spelling, as it allows students to more easily understand and apply the rules of accentuation and syllable division.
In the case of the word adjectival, we find that when separating into syllables the resulting number of syllables is 4. With this in mind, it's much easier to learn how to pronounce adjectival, as we can focus on perfecting the syllabic pronunciation before trying to pronounce adjectival in full or within a sentence. Likewise, this breakdown of adjectival into syllables makes it easier for us to remember how to write it.