Your question is not silly.
Both words you've mentioned have two syllables or sounds.
Each syllable in English contains a vowel or a letter that gives a vowel sound. Some syllables are very short and quiet ( we call this sound minor stress because we hardly hear it).
Often we cant sound a syllable clearly because it has a very short/low (unstressed) sound we call schwa'but it is still a vowel.
The word castle can be divided into two syllables = cast + le
Notice each syllable contains a vowel
The word seven also has two syllables = sev+ en
Notice both syllables have a vowel .
Now look at this word: photography.
This word has four syllables and each syllable can be seen if we break it up to see on this page.
Ex pho to gra phy
This has four syllables but the last doesn't have a vowel. However it does contain a vowel sound (from the y).
The word Canada has three syllables = Ca na da.
Each syllable does contain a vowel as seen on paper, but the last sound is hardly pronounced (this is unstressed and doesn't sound like a vowel , so be careful).
One silly way to count out syllables and to find which sounds are major or minor is to pronounce the word as if you are calling your dog back.
Source Teaching American English Pronunciation by Peter Avery/ Susan Ehrlich