El auxiliar auditivo tiene una batería recargable.

Because auxiliar auditivo is treated as a masculine singular noun phrase here.

• auxiliar can be a noun or an adjective depending on context.
• In this sentence, auxiliar auditivo refers to the device itself, so the whole expression is masculine.
• That is why you get:
  • el auxiliar auditivo
  • not la auxiliar auditiva

A useful thing to remember: the gender of the thing in Spanish does not depend on whether the object is “male” or “female.” It depends on the grammatical gender of the noun.

Literally, it is something like auditory aid or hearing aid.

• auxiliar = aid / assistant / auxiliary
• auditivo = auditory / related to hearing

So even though English usually says hearing aid, Spanish can say auxiliar auditivo.

It is understandable and correct, but in many places audífono is more common in everyday speech.

So you may hear:

• El auxiliar auditivo tiene una batería recargable.
• El audífono tiene una batería recargable.

Both can mean The hearing aid has a rechargeable battery, but audífono is often the more natural everyday word.

Tiene is the third-person singular form of tener (to have).

It matches el auxiliar auditivo, which is he/it in grammatical terms.

Conjugation of tener in the present:

• yo tengo
• tú tienes
• él/ella/usted tiene
• nosotros tenemos
• ustedes/ellos/ellas tienen

So:

• El auxiliar auditivo tiene... = The hearing aid has...

Because batería is a feminine noun.

That means it takes:

• una batería
• not un batería

The ending -a often suggests a noun is feminine, and in this case it is.

In Spanish, descriptive adjectives usually come after the noun.

So:

• una batería recargable = a rechargeable battery

This is the normal word order in Spanish:

• noun + adjective

Compare:

• una casa grande = a big house
• un coche nuevo = a new car
• una batería recargable = a rechargeable battery

Because recargable is one of many adjectives that has the same form for masculine and feminine singular.

So you get:

• un aparato recargable
• una batería recargable

Only the plural changes:

• aparatos recargables
• baterías recargables

Both can relate to batteries, but usage varies by region and by device.

Very generally:

• pila often refers to a small battery, like AA or AAA
• batería often refers to a battery pack or rechargeable battery system

For a device like a hearing aid, batería recargable sounds very natural if it has a built-in rechargeable battery.

Regional usage can vary, so you may hear both in different places.

The accent mark shows where the stress goes: ba-te-RÍ-a.

Without the accent, Spanish pronunciation rules would suggest a different stress pattern. So the written accent is necessary.

Also, notice that -ía often creates a clear extra syllable:

• batería = ba-te-rí-a

In this sentence, yes, it sounds natural to use el.

• El auxiliar auditivo tiene una batería recargable.

Spanish often uses definite articles where English might also use the or sometimes no article at all, depending on context. Here, el identifies the object as the hearing aid.

If you removed it, the sentence would sound incomplete in most normal contexts:

• Auxiliar auditivo tiene una batería recargable ❌

Yes. Cuenta con is another natural way to say has or comes with, especially in product descriptions.

Compare:

• El auxiliar auditivo tiene una batería recargable.
• El auxiliar auditivo cuenta con una batería recargable.

The second version can sound a bit more formal or promotional, while tiene is simpler and more direct.

Yes. The present tense here is being used to state a general characteristic or feature.

So tiene does not mean only right now. It means the hearing aid has this feature in general.

This is very common in Spanish:

• El teléfono tiene buena cámara.
• La computadora tiene 16 GB de memoria.
• El auxiliar auditivo tiene una batería recargable.

It would become:

• Los auxiliares auditivos tienen baterías recargables.

Changes:

• el → los
• auxiliar → auxiliares
• auditivo → auditivos
• tiene → tienen
• una batería → baterías
• recargable → recargables

Notice that in the plural, you would usually drop una because you are speaking generally about multiple devices and their batteries.