Fruit only has 1 syllable. What you have to do is clap your hands while saying the word. You have to see how many claps it takes when you stop saying the word. It's the same thing for any other word.
There is one syllable in "its"
The full form "it is" has two syllables.
How many syllables in guardian?
Clap it out. As you say the word, clap as you make natural pauses in the word. Guardian has 3 syllables Guar-di-an.