Italian

Closer than any other major Romance language. Italian preserves Latin's distinction between long and short consonants (gemination), keeps most final vowels intact (where French dropped them), and has a vocabulary much of which descends transparently from classical Latin. A native Italian speaker can usually puzzle through Renaissance Latin or church Latin without formal study far better than a French or Spanish speaker can.

No, but they're cousins. Italian and Spanish share around 80% of their vocabulary and similar grammatical structure. With patience, written texts are largely readable across the two. Spoken comprehension is harder — Spanish stress and rhythm differ noticeably, and false friends abound (burro means butter in Italian and donkey in Spanish).

What's commonly called 'Italian' is the Tuscan-derived standard, codified through Dante's literary use of Florentine. Across the country, regional languages — Sicilian, Venetian, Neapolitan, Lombard, Piedmontese, Friulian, Sardinian — are still spoken alongside or instead of Standard Italian, and several are not mutually intelligible with the standard. They are sometimes called dialetti but linguistically are separate languages.

Yes, two: masculine and feminine. Most masculine nouns end in -o, most feminine in -a, and adjectives agree with the noun. Plurals follow predictable patterns (-o → -i, -a → -e), with a small set of irregular and invariable forms. Articles, pronouns, and past participles in compound tenses also agree, so gender propagates through whole sentences.

Among the more accessible major languages. Pronunciation matches the spelling almost completely. Vocabulary overlaps heavily with English through Latin and via centuries of cultural and culinary exchange. The slowest piece is the verb system — seven simple tenses, seven compound, plus subjunctive forms in present, past, imperfect, and pluperfect — which most learners spend years internalizing.