Ho comprato un libro scontato.

In Italian, most transitive verbs—verbs that take a direct object—use avere to form the passato prossimo. Since comprare (to buy) directly takes un libro without a preposition, you combine the present of avere with the past participle: • avere (ho) + comprato = ho comprato
By contrast, essere is reserved for unaccusative verbs (e.g. arrivare, nascere) and reflexive constructions.

Italian indefinite articles vary by gender and by the initial sound of the noun:
• un + masculine noun starting with a vowel or most consonants (un libro, un amico)
• uno + masculine noun starting with s+consonant, z, ps, gn, x, y (uno studente, uno zaino)
Since libro begins with a simple consonant l, you use un.

Most Italian adjectives follow the noun they modify. Placing the adjective after the noun:
• Emphasizes a simple descriptive quality.
• Follows the default Italian word order: noun + adjective.
Only a small set of frequent or subjective adjectives (e.g. bello, grande, buono) often precede the noun for stylistic or emotive effects.

Yes. Adjectives in Italian agree with the noun in gender and number. For scontato:
• Masculine singular: scontato
• Feminine singular: scontata
• Masculine plural: scontati
• Feminine plural: scontate
Example: Ho comprato una giacca scontata / Ho comprato due libri scontati.

Technically you can place most adjectives before or after the noun, but:
• Un scontato libro sounds odd to a native speaker.
• Putting scontato before would be non-standard and might sound poetic or archaic.
Stick to un libro scontato for natural, everyday speech.

All convey that the book is discounted, but nuances vary:
• scontato = literally “discounted,” neutral description.
• in saldo = “on sale/clearance,” often used for end-of-season or storewide sales.
• in offerta = “on offer,” common in advertising; may imply a temporary promotion.
In most contexts they can be used interchangeably, but scontato focuses on the adjective form.

Pronunciation: /skonˈtaːto/
• scon – like the English “scone” without the final e.
• ˈta – stressed syllable: strong “ta.”
• to – light “to.”
So you say: sCON-ta-to, with the primary stress on the second syllable.

Yes. Acquistare is a more formal synonym of comprare.
• Ho acquistato un libro scontato = “I purchased a discounted book.”
• Ho comprato un libro scontato = “I bought a discounted book.”
Both are correct; choose based on register (everyday vs. slightly more formal).