"Si prevede un aumento dei prezzi" looks like it should have a subject somewhere, someone doing the predicting, but there isn't one. The sentence means "a price increase is expected," and the small word doing all the structural work is "si," attached to a verb in a way most app courses introduce briefly as reflexive ("mi lavo," I wash myself) and then never revisit in this second, completely different job. Real Italian news leans on this second use constantly, and recognizing it as its own construction, not a stray reflexive pronoun, is worth doing deliberately.
The construction hiding behind an ordinary reflexive verb
This use of "si," called si passivante, functions as Italian's main substitute for the passive voice in everyday and journalistic writing: instead of "prices are expected to rise" naming no agent through a passive construction the way English does, Italian attaches "si" to an active verb and lets the following noun act as the grammatical subject the verb agrees with. "Si vendono molte case in centro" (many houses are sold downtown) has "case" (houses) as the actual grammatical subject, which is why the verb is plural, "vendono," even though the sentence reads left to right as if "si" were doing the selling.
Why news leans on it so heavily
This construction lets a writer state a fact, a trend, or a claim without committing to who specifically is doing it or saying it, which is exactly the kind of framing news writing needs constantly: general trends, common practices, and claims attributed to no one in particular in a way that would sound both officially neutral and unnatural if fully spelled out with a passive construction. "Si stima che il numero sia sottostimato" (it's estimated that the number is understated) reports an estimate without naming whose estimate it is, a genuinely common move in economic and statistical reporting where the source is a general consensus rather than one named body.
The ambiguity worth watching for
"Si" carries at least three separate jobs in Italian, reflexive ("si lava," she washes herself), reciprocal ("si salutano," they greet each other), and this impersonal-passive use, and a sentence occasionally leaves genuine room to misread one for another until you check what the subject actually is. "Si dice che" (it is said that) can look structurally similar to a reflexive construction to an unpracticed eye, but there's no plausible reflexive reading available, since "dire" (to say) applied reflexively to an unnamed "it" makes no sense, which is itself a useful check: if the reflexive or reciprocal reading doesn't make sense for the verb involved, the impersonal-passive reading is almost certainly the right one.
A full sentence, taken apart
Take a realistic news sentence: "Si segnalano ritardi sulla linea ferroviaria a causa del maltempo." Broken down: "si segnalano" (delays are being reported), "ritardi" (delays, plural, the actual grammatical subject, matching the plural verb form), "sulla linea ferroviaria" (on the rail line), "a causa del maltempo" (due to bad weather). Nobody is named as doing the reporting, and that's the entire point of the construction: delays are being reported, full stop, without the sentence needing to specify by whom. Restated as a hypothetical fully-agented English sentence, "authorities report delays on the rail line due to bad weather," makes the substitution visible: Italian's si passivante does the same reporting job without inventing or naming an agent the original source never specified either.
Singular versus plural, and why it isn't a free choice
Because the noun following the verb is the true grammatical subject, the verb has to agree with it in number, which is the detail that most reliably tells si passivante apart from a reflexive reading at a glance. "Si vende una casa" (a house is sold, or "one sells a house") keeps the verb singular because "casa" is singular; "si vendono molte case" switches to the plural "vendono" purely because "case" is plural, even though "si" itself never changes. A learner expecting "si" to behave like a fixed, invariant marker the way a reflexive pronoun often feels can be thrown by seeing the verb change form article to article depending on nothing but what follows it, when in fact that agreement is the single most reliable tell that a construction is passivante rather than reflexive or reciprocal.
How this changes what a sentence is willing to claim
Once "si" plus a verb agreeing with a following noun stops registering as an unusual reflexive-looking construction and starts registering as ordinary impersonal reporting, a real share of Italian news sentences that initially look subjectless resolve immediately. The broader payoff is recognizing what kind of claim the sentence is making: a si passivante construction is, by its nature, reporting something as general or consensus-level rather than attributed to one named source, which matters for the same reason tracking who's making a claim matters in any language's journalism, except here the signal that no one specific is named is built directly into the grammar rather than left to a reporting verb like "sources say."