Learn Hardcore French: Dans la brochure, on trouve aussi un plan du quartier et les horaires de chaque spectacle du festival. - In the brochure, you also find a map of the neighborhood and the timetable of each festival show.

“In the brochure, you can find…”
“In the brochure, we find…”
“In the brochure, there is / there are…” (functionally similar to il y a here)

Using on is more neutral and more natural than nous trouvons in this kind of explanatory sentence.
Nous trouvons would sound like “we (the speakers) find,” which is more personal and less general.

You could also say:

Dans la brochure, il y a un plan du quartier…
→ grammatically correct, very common too, just a slightly different structure: “there is / there are” instead of “one finds.”

Why is it trouve and not trouvent?

The subject on always takes the third person singular form of the verb, the same as il/elle:

il trouve
elle trouve
on trouve

So you must say on trouve, never on trouvent.

Even when on actually refers to more than one person (“we”), the verb still stays singular in form:

On est allés au cinéma. (We went to the cinema.)
→ est, not sommes, because of on.

What tense is trouve here, and why is it used?

Trouve is present tense (présent de l’indicatif).

In French, the present tense is often used to talk about what a document, book, film, website, etc. contains or says, as a kind of timeless fact:

Dans ce guide, on explique les règles.
Sur ce site, on trouve des informations utiles.

So Dans la brochure, on trouve… means “In the brochure, you (can) find…” in a general, always-true way.

Why is it Dans la brochure and not Sur la brochure or En la brochure?

dans = in / inside
You use this because the information is inside the brochure (in the pages).

Sur la brochure (literally “on the brochure”) would usually refer to something on the cover or surface, e.g.:

Sur la brochure, il y a une belle photo de la ville.
(On the brochure cover, there is a nice picture of the city.)

En la brochure is simply not correct in French. The normal preposition here is dans for the contents of a brochure, book, magazine, etc.

Why is aussi placed after trouve (in on trouve aussi)? Could I move it?

In the sentence, we have:

on trouve aussi un plan du quartier…

Here, aussi is placed right after the verb trouve, which is very typical:

On trouve aussi… = You also find / There is also…

You can move aussi, but the meaning or emphasis changes slightly:

Dans la brochure, on trouve un plan du quartier aussi.
→ Possible, but sounds more like adding “the map as well” at the very end for emphasis; less neutral.
Dans la brochure, on y trouve aussi…
→ Very natural too, adding y (“there”), meaning “In the brochure, you also find there…”

The most neutral and standard pattern in this kind of sentence is exactly what you see:

[subject] + [verb] + aussi + [object]
→ On trouve aussi un plan du quartier…

Why is it un plan du quartier and not une carte du quartier?

French distinguishes plan and carte:

un plan = a map of a town, city, building, metro system, etc.
(large scale, detailed, more local)
une carte = a map of a country, region, world, or a playing card / menu.

So a map of a neighbourhood or district is normally un plan du quartier, not une carte du quartier.

Examples:

un plan de Paris (street map of Paris)
une carte de France (map of France)

What exactly does quartier mean here?

Quartier is:

a part of a town or city, a neighbourhood / district.
masculine noun: un quartier, le quartier.

In un plan du quartier, it refers to the local area around the festival, the part of the town where it takes place.

Rough equivalents in English: neighbourhood, district, area (urban context).

What is du in un plan du quartier? Why not just de quartier?

Du is the contraction of de + le:

de + le quartier → du quartier

We use de + le (→ du) because we’re saying “the neighbourhood”, not just “neighbourhood” in general.

Compare:

un plan du quartier = a map of the (specific) neighbourhood
un plan de quartier would sound more like “a neighbourhood map” in a very general, descriptive way, not of a specific, known area.

Here, we are talking about the particular neighbourhood where the festival is, so du quartier is the natural choice.

What does les horaires mean, and why is it plural?

Un horaire / des horaires is:

a schedule, timetable, or set of times (for trains, shows, opening hours, etc.).

In practice, French very often uses the plural:

les horaires du bus = the bus times / schedule
les horaires d’ouverture = opening hours

In the sentence:

les horaires de chaque spectacle
= the times / schedule for each show.

Even though English often says “the schedule” (singular), in French, talking about multiple time slots, we naturally use les horaires (plural).

Why is it les horaires de chaque spectacle when chaque is singular?

Grammar here:

les horaires → plural (there are many times overall)
de chaque spectacle → “of each show”; chaque is always singular in French.

So the idea is:

les horaires (all the time slots together)
de chaque spectacle (belonging to each individual show)

You cannot say chaques spectacles; chaque never has a plural form:

chaque spectacle (each show)
chaque jour (each day)
chaque personne (each person)

How should I understand the grouping in les horaires de chaque spectacle du festival? Who modifies what?

The structure is layered like this:

les horaires
→ the schedules / times
de chaque spectacle
→ of each show
du festival = de + le festival
→ of the festival

So we can paraphrase:

les horaires (the schedules)
de chaque spectacle (of each show)
du festival (which belongs to / is part of the festival)

In English: “the schedule for each show in the festival” or “the times of every festival performance.”

Could we say les horaires de tous les spectacles du festival instead of de chaque spectacle?

Yes, you could say:

les horaires de tous les spectacles du festival
= the schedules of all the shows of the festival.

Difference:

chaque spectacle → emphasizes each individual show separately.
tous les spectacles → emphasizes the whole set of shows together.

Both are correct; the original just highlights the idea that every single show has its own listed time.

Could we also say Dans la brochure, on y trouve aussi un plan du quartier…? What’s the difference?

Yes, that’s also correct:

Dans la brochure, on trouve aussi un plan du quartier…
Dans la brochure, on y trouve aussi un plan du quartier…

In the second version, y refers back to dans la brochure (“there, in it”).

The difference is small:

on trouve → neutral, simple: “one finds / you find.”
on y trouve → slightly more explicit: “one finds there,” reinforcing the idea that the brochure is the place where you find this information.

Both are idiomatic; the original is just a bit lighter and more common in a simple descriptive sentence.