In English, we can use nouns as adjectives to answer the question, "what kind?" For example, "dog days" are the hottest days of summer. In this case, it's not really comparing the dog to the heat, but comes from the star, Sirius, who was Orion's dog in the constellations. It rises at the same time as the sun on the hottest days in the northern hemisphere. The Romans got this from the Greeks, and called these days, "dies caniculares" (dog days).
In terms of grammar, we know "dog" is a noun, but here, we use it as an adjective to describe "days," without giving it a different ending. We don't say, "dogful" days, "doggy days," or even "dog-like days." So this is a phenomenon that is present in many situations in English.
Let's remember here — because we don't have to think about it — that in English, we put the noun-as-adjective before the noun it describes. Sometimes the noun-as-adjective merges with the noun and becomes a compound word and sometimes not: laundry room, dishwasher, picture frame, bicycle rack.
We have the same phenomenon in Italian. The big difference is that the order is inverse. First, we have the noun, then we have the noun-as-adjective. To connect with our example of "dog days," we turn to an expression that is very common in Italian, and in fact, it crops up in an episode of Sposami.
E poi una notte, che io dormivo sotto il cavalcavia e faceva un freddo cane, quella notte io credevo che sarei morto...
And then, one night, when I was sleeping under an overpass, and it was freezing cold, that night, I believed I would die...
Captions 6-8, Sposami EP 4 - Part 19Play Caption
And here is a more mundane example:
Lo abbiamo fatto pure in conferenza stampa l'altro ieri
We even did it at the press conference the day before yesterday
Caption 22, Animalisti Italiani Walter Caporale - Part 2Play Caption
The real noun is conferenza (conferenza). What kind of conference? una conferenza stampa (a press conference).
This difference in word order is tricky sometimes, and it is just as tricky for Italians attempting to speak English correctly.
English is a popular language, and Italians use it in publicity and signage. But sometimes the word order difference escapes them. The name of a riding school in Tuscany is "Planet Horse." This is because, in general, for an Italian, the adjective (even if it is a noun-as-adjective, as in this case) comes after the noun. What they were trying to say, even though it sounds bad, is "Horse Planet" — the planet of horses. We might say, "Horse World." They, of course, translated it from Italian: Pianeta cavallo.
In some cases, both the noun-as-adjective and the adjective form of a noun can work:
Let's take the noun bestia (beast, animal).
We can say: Fa un caldo bestia (it is incredibly hot) or Fa un caldo bestiale (it's beastly hot). Using the noun as an adjective in this case is more colloquial, but they are both acceptable.
Of course, in Italian, when answering the question, "What kind?" we often use a preposition, such as di or da, or an "articulated preposition," such as del, della, delle, or degli before the "descriptive" noun. These prepositions usually mean "of."
Il bidone della spazzatura (the garbage can)
Il professore di matematica (the math teacher)
Il forno da pizza (the pizza oven)
We can't always use a noun as an adjective, but it is important to know that it exists as a phenomenon, and to recognize it when it occurs.