Antes de jantar, a gata esfrega-se no meu casaco e mia.

Because jantar here is a verb in the infinitive, not a noun.

In Antes de jantar, the structure is antes de + infinitive, which means before doing something. So jantar means to have dinner / to eat dinner.

Compare:

• Antes de jantar = before having dinner
• Antes do jantar = before dinner (literally before the dinner)

Both can be possible in Portuguese, but this sentence uses the verb structure.

Because antes de is the normal pattern before a noun or an infinitive.

Very common combinations are:

• antes de sair = before leaving
• antes de dormir = before sleeping
• antes do almoço = before lunch
• antes da aula = before class

So antes de jantar is completely standard.

Grammatically, it literally means before eating dinner / before having dinner.

But in real usage, it often functions very much like before dinner, especially when the exact subject is not important.

In this sentence, it does not necessarily mean the cat is the one having dinner. It can simply set the time frame: before dinner time or before we/I have dinner, depending on context.

That kind of vagueness is normal in Portuguese.

Because gata is the feminine form of gato.

• o gato = the male cat / the cat
• a gata = the female cat

So the sentence is specifically talking about a female cat.

The article also agrees with the noun:

• a gata
• not o gata

This is because the verb is being used reflexively: esfregar-se = to rub oneself.

Here, se refers back to a gata:

• a gata esfrega-se = the cat rubs herself

In European Portuguese, in a normal affirmative main clause, it is very common for the clitic pronoun to come after the verb:

• esfrega-se

This is called enclisis.

In European Portuguese, a gata esfrega-se is the more standard choice in this kind of sentence.

Why?

Because there is no word here that strongly triggers the pronoun to come before the verb. In EP, affirmative main clauses usually prefer:

• verbo + pronome
• so: esfrega-se

You may hear se esfrega more often in Brazilian Portuguese, or in contexts where a word triggers proclisis (pronoun before the verb), such as:

• não se esfrega
• quando se esfrega
• já se esfrega

But in this sentence, esfrega-se is the expected EP form.

It means the cat rubs herself on / against my coat.

The core idea is:

• esfregar = to rub
• esfregar-se = to rub oneself

With em + a thing, it can express rubbing against that surface/object.

So:

• esfrega-se no meu casaco = rubs herself on my coat / against my coat

In natural English, rub against is often the most idiomatic translation, even if Portuguese uses em here.

Because no is a contraction:

• em + o = no

Since casaco is masculine singular, the definite article is o. So:

• em o meu casaco → no meu casaco

This kind of contraction is required in standard Portuguese.

Other common ones are:

• em + a = na
• em + os = nos
• em + as = nas

So:

• na casa
• nos livros
• nas mãos

In European Portuguese, possessives are very often used with a definite article:

• o meu casaco
• a minha gata
• os meus livros

After a preposition, that article is still there, and it often contracts:

• em + o meu casaco → no meu casaco
• de + a minha casa → da minha casa

So although you do not see o separately, it is still present inside no.

This use of the article before possessives is especially typical of EP.

Because Antes de jantar is an introductory time phrase.

The comma helps separate that opening phrase from the main clause:

• Antes de jantar, a gata esfrega-se no meu casaco e mia.

This is very natural in writing. With a short introductory phrase, the comma can sometimes be omitted, but here it is perfectly normal and helps readability.

Mia is the 3rd person singular present tense of miar (to meow).

The subject is a gata, which is she / it, so the verb must be 3rd person singular:

• eu mio
• tu mias
• ele/ela mia

So:

• a gata mia = the cat meows

It is in the present tense, which can describe:

• something happening now, or
• a habitual action

In a sentence like this, it often sounds like a habitual or typical action.

It is pronounced with two syllables:

• mi-a

So it is not like a single English syllable. The vowel sequence is pronounced separately.

Likewise, miar is also pronounced with a clear break between the vowels:

• mi-ar

That is useful to remember because learners sometimes try to compress it too much.

The feminine marking appears in both the article and the noun:

• a = feminine singular article
• gata = feminine singular noun

The verbs do not change for grammatical gender:

• a gata mia
• o gato mia

So gender affects:

• articles
• adjectives
• some nouns/participles

But not the finite verb form here.

Yes. The present tense in Portuguese often works that way.

So a gata esfrega-se no meu casaco e mia can mean:

• the cat is rubbing herself on my coat and meowing in a vivid present description, or
• the cat rubs herself on my coat and meows as something she typically does

Without more context, both are possible, but many learners should notice that the Portuguese present tense often covers both simple present and some uses that English might express differently depending on context.