Syllables are individual sounds within a word. Every syllable has a vowel sound.
Day has one syllable
Apple (ap - ple) has two syllables
Beautiful (beau - ti - ful) has three syllables
To help you figure out how many syllables a word has remember ...
You learned how to clap and/or snap the syllables of words in elementary school.
Each time your jaw drops when you are speaking a word counts as a syllable.
If you are not sure after trying these two strategies, look the work up in the Dictionary. There is a dot between letters to show the syllable break.
If you still need help, try HowManySyllables.com, SyllableCounter.org, or SyllableCounter.net. Type in the word you are trying to figure out.