Tuoi is masculine second person singular possesive (i.e. informal you), tua feminine second person singular. Suoi and sua are the same for the third person singular (he/she) possessive. Don't forget that the gender used corresponds to the grammatical gender of the thing owned, not the gender of the person who owns it.
Yeah, what he said (although Loro is the 3rd person plural nominative pronoun, so "they" not "them" [which is the objective pronoun]). Basically sono is used with loro and anything that can be replaced with loro. So to translate into English:
I guanti sono i tuoi (The gloves are yours) Loro sono i tuoi (They [the gloves] are yours) So we see that we can replace "the gloves" a third person plural subject with the pronoun (pronoun literally means "in place of a noun") loro, meaning we conjugate with the third person plural of the verb "esse" which in this case is "sono"
Basically in most (but not all) western grammar you will find 3 persons, which are divided into singular and plural: 1st Person is referencing the self, singular is "I" (io in Italian), "we" (noi) for plural. 2nd Person references someone you're talking to directly "you" (tu) for singular, "you/you all/youse/all y'all" (voi) for plural. 3rd person references another party outside the conversation "he/she/it" (lui/lei) for singular, and "they" (loro) for plural.
In English as well as Italian we conjugate that is, change the form of the verb to match with the person and number we're referencing. English is a bit more simplistic in the conjugations; for most verbs we only have 2 or 3 different present-indicative conjugations for any given verb. For example "to be" uses: I am/you are/he is/we are/they are. "To sing" is even simpler still: I sing/you sing/he sings/we sing/they sing. Italian, by contrast has 5 or 6 distinct forms for each of its verbs. More to memorize, sure, but it also means they're more precise in whom they're talking about, meaning they can (and do) eliminate the pronoun entirely from the sentence, because it's usually implicit in the verb. Spanish does this too, as did their mother tongue Latin.
Language rules construct the sentence around the
subject. In Italian and in English the
subject usually comes before the verb. In your sentence the subject is "
they". In the original sentence, the subject is "
I guanti" = "
The gloves". The object on the other hand usually comes after the verb. In your sentence the object is "your gloves". In the original sentence, the object is "i tuoi" = "yours". While both sentences are semantically the same, grammatically they are VERY different.
Determiner + noun + verb + (determiner) + possessive pronoun
I guantisono i tuoi =
The glovesare yours
(Nominative pronoun) + verb + (determiner) + possessive adjective + noun
Loro) sono (i) tuoi guanti =
Theyare your gloves