- эти мои очки = these glasses of mine, these my glasses (glasses are plural so you have to use the plural form, эти, if you want «эти» to be a modifier of «очки»)
- Это мои очки. — These are my glasses. (when «это» is used to introduce a noun, it doesn't change)
- это мои очки — ??? (I can't think of a context when this has a meaning, except the previous one.)
Hey, I have a good video to watch about this. Let me know if it helps.
No, it can mean either. «Очки́» is a pluralia tantum noun, it's not used in singular in this meaning. Just like the English noun.
Singular form means something completely different. I guess it's simpler to show this in pictures.
glasses — очки́ (only plural form)
glass — стака́н (it can be both singular and plural, Russian plural is стака́ны):
очко́ — point (it can be both singular and plural). I can't find a good picture, but 'hit points' in games are often translated «очки́ жи́зни» (points of life):
So, «glass» only means a thing to drink from. «Glasses» can mean either spectacles and things to drink from.
«Очко́» means point. «Очки́» can mean either spectacles or points.
Russian nouns have several forms called cases. It’s similar to English pronouns (she is nice — I know her; she and her are different cases), but in Russian, all the words have case forms.
Очки́ is either nominative plural or accusative plural. Nominative plural is used (i.a) when glasses are a subject of the sentence (очки́ помога́ют лу́чше ви́деть ‘glasses help to see better), (i.b) in ‘X is Y’ sentences for both X and Y. Accusative plural is used (ii.a) when glasses is a direct object of a positive sentence (он но́сит очки́ ‘he wears glasses’).
Очко́в is genitive plural. It’s used (i) in the meaining ‘of glasses’ (опра́ва очко́в ‘frame of glasses’), (ii) when talking about quantities (не́сколько очко́в ‘several glasses’, «не́т очко́в» ‘no glasses’), (iii) as an direct object of a negative sentence (он не но́сит очко́в ‘he doesn’t wear glasses’).