I don't understand.
Gli is plural for the I is plural for the
but in what case would you choose? both are masculine..
When the first letter of the noun is a vowel, then you use gli. That's why you have l'uomo (singular: man) and gli uomini (plural: men).
But when the first letter of the noun is a consonant, you use the i in front. So il gatto (the cat) is i gatti (the cats). Hopefully this helps! I am on my second day of learning Italian.