La cámara de aire pierde aire.

Because cámara is a feminine noun in this meaning, so it takes la.

• la cámara
• una cámara

Be careful: el cámara can exist too, but it means the camera operator / cameraman in some contexts. In your sentence, cámara means a physical chamber / inner tube, so it is feminine: la cámara.

In this sentence, cámara de aire is a fixed expression meaning inner tube or air chamber, depending on context.

In Spain, it is commonly used for the inflatable tube inside a tyre, for example on a bicycle. Grammatically, you can think of it as:

• cámara = chamber
• de aire = of air / air-filled

But together, it functions as one unit: cámara de aire.

De often links two nouns in Spanish, where English might use:

• of
• a noun used like an adjective
• a compound noun

So cámara de aire is literally something like air chamber or chamber of air.

This pattern is very common in Spanish:

• gafas de sol = sunglasses
• cepillo de dientes = toothbrush
• botella de agua = water bottle

So de is just the normal way Spanish connects these ideas.

Because the subject is la cámara de aire, which is third person singular, so the verb perder has to be conjugated as pierde.

Present tense of perder:

• yo pierdo
• tú pierdes
• él / ella / usted pierde
• nosotros perdemos
• vosotros perdéis
• ellos / ellas / ustedes pierden

So:

• La cámara de aire pierde aire.
• one thing is losing air
• therefore: pierde

Also note that perder is a stem-changing verb: e → ie in many forms, which is why it is pierde, not perde.

Because the two instances of aire do different jobs.

1. In cámara de aire, aire is part of the noun phrase naming the object.
2. In pierde aire, aire is what the object is losing.

So even though the same word appears twice, it is not redundant in Spanish. The sentence is structured like this:

• La cámara de aire = the inner tube / air chamber
• pierde aire = is losing air

This repetition sounds completely natural.

Because aire here is being used as an uncountable / mass noun, like water, smoke, or gas in English.

Spanish often omits the article in this kind of case:

• pierde aire = loses air
• pierde agua = loses water
• suelta humo = gives off smoke

If you added an article, it would usually sound less natural or would change the nuance.

Yes. That is also correct, and it sounds very natural.

The difference is mainly one of focus:

• La cámara de aire pierde aire.
  = a general statement / it leaks air / it is losing air
• La cámara está perdiendo aire.
  = it is in the process of losing air right now

In everyday Spanish, the simple present often covers situations where English might use is losing. So the original sentence is perfectly normal.

Spanish often expresses this idea with perder aire, literally to lose air. That is a very common and natural way to say that a tyre or inner tube has a leak.

You may also hear related expressions such as:

• tener una fuga = to have a leak
• pincharse = to get punctured
• desinflarse = to go flat / deflate

But pierde aire is simple, common, and idiomatic.

Aire is normally a masculine noun: el aire.

However, in your sentence there is no article before the second aire, because it is being used as a mass noun after the verb perder:

• pierde aire

So this is not about gender changing. It is simply that no article is needed there.

When you do use an article, it is masculine:

• el aire frío
• el aire acondicionado

In standard Peninsular Spanish, pierde is pronounced approximately:

• PYER-de

A few helpful points:

• ie forms one syllable with a glide, sounding like ye in yes
• the r is a tapped Spanish r, not a strong English r
• the d in the middle is softer than in English

So it is roughly PYER-de, with the stress on the first syllable.

Yes, very often Spanish can omit the subject when it is understood.

So instead of:

• La cámara de aire pierde aire.

you might hear:

• Pierde aire.

That is possible if the context already makes it clear what it is. Spanish does this a lot because the verb ending already tells you the person and number.

But if you want to be clear and explicit, the full sentence with La cámara de aire is completely fine.