La ambientación temática cambia la sala.

The subject is La ambientación temática.

That whole noun phrase is doing the action, and the verb is cambia.

A quick way to see it:

• La ambientación temática = subject
• cambia = verb
• la sala = direct object

So the sentence structure is basically:

[Subject] + [verb] + [object]

Because the subject is singular.

The main noun in the subject is ambientación, which is singular, so the verb must also be singular:

• la ambientación → singular
• cambia → third person singular

If the subject were plural, then you would use cambian:

• Las ambientaciones temáticas cambian la sala.

Ambientación is a feminine singular noun.

It comes from the idea of creating an atmosphere, setting, or environment. In many contexts, it can refer to:

• decor
• atmosphere
• styling
• thematic setup
• set design, depending on context

In this sentence, it is the thing that causes the room to feel different.

Because temática is describing the noun ambientación.

In Spanish, adjectives often come after the noun:

• ambientación temática = thematic ambiance / thematic decor / themed setting

This is very normal word order in Spanish.

English often puts adjectives before the noun, but Spanish commonly places them after:

• casa grande
• idea interesante
• ambientación temática

Because it has to agree with ambientación, which is feminine singular.

Agreement in Spanish means the adjective matches the noun in gender and number:

• ambientación = feminine singular
• so the adjective must be temática

Compare:

• el ambiente temático → masculine singular
• la ambientación temática → feminine singular
• las ambientaciones temáticas → feminine plural

Spanish uses definite articles more often than English does.

Here:

• La ambientación temática = the thematic ambiance/decor
• la sala = the room/hall/lounge

Even if English might sometimes drop the, Spanish often keeps it. This is completely normal.

Also, each noun phrase needs its own article here:

• one article for the subject
• one article for the object

Yes.

Here, cambiar is transitive, meaning it acts directly on something:

• cambiar la sala = to change the room

So la sala is the direct object.

Spanish cambiar can be used in different ways:

• Cambiaron el plan. = They changed the plan.
• La ciudad cambió. = The city changed.
  In this case it is intransitive.

In your sentence, it clearly means changes/transforms the room.

Sala can mean different things depending on context, such as:

• room
• living room
• lounge
• hall
• sitting room

In Latin America, sala often refers to the living room in a house, but it can also mean a general room or hall in other contexts.

So the exact English word depends on where the sentence comes from.

No, that changes the meaning.

• La ambientación temática cambia la sala.
  = The thematic decor/ambiance changes the room.

• La sala cambia.
  = The room changes.

In the original sentence, the room is receiving the action. In La sala cambia, the room itself becomes the subject.

So word order matters because it changes who is doing the action.

Yes. Depending on style, Spanish might also use verbs like:

• transforma
• modifica
• renueva

For example:

• La ambientación temática transforma la sala.

That can sound a little stronger or more natural in some contexts. But cambia is still grammatically correct and easy to understand.

The written accent in ambientación shows the stress falls on the final syllable: -ción.

Without getting too technical, many nouns ending in -ción have a written accent:

• información
• decoración
• ambientación

So you pronounce it roughly like: am-bien-ta-CIÓN

The accent mark helps show the correct stress pattern.

Yes, it is understandable and grammatically correct.

That said, how natural it feels can depend on context. In advertising, interior design, event planning, or descriptions of decor, it sounds quite normal.

In everyday speech, a speaker might also say something like:

• La ambientación temática le cambia mucho el aspecto a la sala.
• La ambientación temática transforma la sala.

So the original sentence works, especially in descriptive or promotional language.