O personal trainer ajusta a série de exercícios.

O is the masculine singular definite article, meaning the.

It is used here because personal trainer is being treated as a masculine singular noun in Portuguese:

• o personal trainer = the personal trainer

Portuguese articles must agree with the gender and number of the noun:

• o = masculine singular
• a = feminine singular
• os = masculine plural
• as = feminine plural

In Brazilian Portuguese, personal trainer is very commonly used as a borrowed expression from English, especially in fitness contexts.

So even though Portuguese has other ways to express the idea, Brazilians often say:

• o personal trainer
• a personal trainer

Notice that the article changes according to the person’s gender, but personal trainer itself usually stays the same.

Ajustar is the infinitive form, meaning to adjust.

In the sentence, the verb is conjugated for he/she/it in the present tense:

• eu ajusto = I adjust
• você/ele/ela ajusta = you/he/she adjusts
• nós ajustamos = we adjust

Since the subject is o personal trainer, the correct form is ajusta.

In Portuguese, the simple present tense can often cover both ideas, depending on context.

So ajusta can mean:

• adjusts
• is adjusting
• sometimes even does adjust

If you specifically want to emphasize an ongoing action, Portuguese often uses:

• está ajustando = is adjusting

But in a simple sentence like this, ajusta is completely natural.

Because série is a noun, and here it is also definite: the series/set.

So:

• a série = the series or the set

It uses a because série is a feminine singular noun.

This sentence has two definite articles:

• o personal trainer
• a série

That is very normal in Portuguese.

In a fitness context, série de exercícios usually means something like:

• exercise routine
• set of exercises
• exercise program
• training set/plan

The exact English choice depends on context.

Literally, it is:

• série = series / set
• de exercícios = of exercises

So the structure is basically a series of exercises.

De often means of.

Here it links the two nouns:

• série de exercícios = series of exercises

This is a very common Portuguese pattern:

• copo de água = glass of water
• aula de português = Portuguese class
• lista de nomes = list of names

So de is simply connecting série to exercícios.

Because the sentence is talking about more than one exercise.

• exercício = exercise
• exercícios = exercises

So:

• a série de exercício would sound odd in this context
• a série de exercícios is the natural expression

A workout routine or set usually contains multiple exercises, so the plural makes sense.

The sentence follows the standard Portuguese order:

Subject + verb + object

• O personal trainer = subject
• ajusta = verb
• a série de exercícios = object

This is the same basic order as in English:

• The personal trainer adjusts the exercise routine.

Yes, you may see or hear treinador pessoal, and people would understand it. However, in Brazil, personal trainer is much more common in everyday fitness language.

So:

• O personal trainer ajusta a série de exercícios. = very natural
• O treinador pessoal ajusta a série de exercícios. = understandable, but less common in many real-life situations

If your goal is natural Brazilian usage, personal trainer is a very good choice.

The acute accent in série shows the stressed syllable and helps indicate the vowel quality.

It is pronounced roughly like:

• SEH-ree-ee in Brazilian Portuguese

The stress falls on the first syllable:

• SÉ-rie

Without the accent, the pronunciation rules would suggest something different. The accent helps show the correct stress pattern.

Yes. Série can mean series in different contexts, including:

• a TV series
• a sequence
• a set
• a series of exercises

So the meaning depends on context.

In this sentence, because of de exercícios, it clearly refers to a workout set/routine, not a TV show.

It could be either. The present tense in Portuguese is flexible.

Depending on context, it might mean:

• a general fact: The personal trainer adjusts the exercise routine
• a habitual action: The personal trainer usually adjusts the routine
• a current action: The personal trainer is adjusting the routine

Context tells you which meaning is intended.

Normally, no. In standard Portuguese, you would usually keep the article:

• O personal trainer...

Dropping the article can sound unnatural here. Portuguese uses definite articles more often than English does, especially before common nouns.

So the natural version is:

• O personal trainer ajusta a série de exercícios.