A lanterna frontal tem pilhas novas.

A is the feminine singular definite article, meaning the.

It is used because lanterna is a feminine singular noun in Portuguese. So:

• a lanterna = the flashlight / the lamp
• masculine equivalent would use o

In this sentence, A lanterna frontal means the headlamp or the head torch.

In Portuguese, adjectives usually come after the noun, unlike in English.

So:

• lanterna frontal = literally flashlight frontal
• natural English translation: headlamp / head torch

This noun + adjective order is very common in Portuguese:

• casa grande = big house
• carro novo = new car

So frontal follows lanterna because that is the normal adjective position.

Tem is the 3rd person singular form of the verb ter, which usually means to have.

So:

• eu tenho = I have
• tu tens = you have
• ele/ela tem = he/she/it has

In this sentence, tem agrees with A lanterna frontal, which is singular:

• A lanterna frontal tem... = The headlamp has...

Portuguese often leaves out subject pronouns when the verb form already makes the subject clear.

So instead of saying:

• A lanterna frontal ela tem pilhas novas

Portuguese normally just says:

• A lanterna frontal tem pilhas novas

The noun phrase A lanterna frontal already tells you what the subject is, so adding ela would usually be unnecessary.

In European Portuguese, pilhas usually means small batteries, especially the kind you put into devices and can replace, such as AA or AAA batteries.

Bateria often refers to:

• a larger battery
• a rechargeable battery pack
• a car battery
• a phone or laptop battery

So for a headlamp with replaceable batteries, pilhas is the natural choice.

Because novas must agree with pilhas in gender and number.

Pilhas is:

• feminine
• plural

So the adjective must also be feminine plural:

• novo = masculine singular
• nova = feminine singular
• novos = masculine plural
• novas = feminine plural

That is why the sentence has pilhas novas.

Because adjectives usually come after the noun in Portuguese.

So:

• pilhas novas = new batteries

This is the normal and neutral order. In some cases Portuguese can place adjectives before the noun, but that often changes the tone or emphasis. Here, pilhas novas is the standard choice.

Because the verb agrees with the subject, not with the thing being possessed.

The subject is:

• A lanterna frontal = singular

The object is:

• pilhas novas = plural

So the verb must be singular:

• A lanterna frontal tem pilhas novas.

If the subject were plural, the verb would change:

• As lanternas frontais têm pilhas novas.

Yes, lanterna frontal is a normal and clear European Portuguese term for a lamp worn on the head.

You may also hear just frontal in context, especially when people already know you are talking about that kind of lamp.

So all of these can make sense depending on context:

• lanterna frontal
• frontal (more informal or shortened)

Not with the same meaning.

• tem here means has
• há and existem mean there is / there are

So:

• A lanterna frontal tem pilhas novas. = The headlamp has new batteries.
• Há pilhas novas. = There are new batteries.
• Existem pilhas novas. = New batteries exist / There are new batteries.

Those are different ideas. The original sentence is specifically about what the headlamp possesses.

In European Portuguese, tem is pronounced roughly like tãj or tẽj, with a nasal sound.

A few pronunciation points:

• the e is nasal
• the final m is not pronounced like a strong English m
• instead, it helps nasalise the vowel

This is the same kind of nasal ending you hear in many Portuguese words ending in -em or -ém.