L'aria entra nella camera d'aria dalla valvola Presta.

Because Italian usually uses the definite article more often than English.

• aria = air
• l'aria = the air

In a general statement like this, Italian normally says l'aria where English often just says air.

Also, aria is a feminine singular noun, and before a vowel la becomes l':

• la casa
• l'aria

So l'aria is just la aria shortened.

Entra is the third person singular of entrare = to enter / to go in.

Here the subject is l'aria, which is singular, so the verb must also be singular:

• l'aria entra = the air enters

A quick pattern:

• entro = I enter
• entri = you enter
• entra = he/she/it enters
• entriamo = we enter
• entrate = you all enter
• entrano = they enter

So entra is used because air is being treated as one thing.

Nella is a contraction of:

• in + la = nella

Here it means into / in the.

So:

• nella camera d'aria = into the inner tube / in the inner tube

Italian often combines prepositions with definite articles:

• in + il = nel
• in + lo = nello
• in + la = nella
• in + i = nei
• in + gli = negli
• in + le = nelle

Since camera is feminine singular and takes la, you get nella camera.

Camera d'aria is the normal term for an inner tube.

Literally, it is something like:

• camera = chamber
• d'aria = of air

So literally it means air chamber, but in context it refers to the inner tube of a tire.

This is a good example of how Italian often uses a phrase whose literal meaning is different from the natural English term.

Because d' is short for di before a vowel.

• di aria becomes d'aria

So:

• camera d'aria = chamber of air

This apostrophe is very common in Italian when di comes before a word beginning with a vowel:

• l'idea d'amore
• un po' d'acqua
• camera d'aria

Dalla is a contraction of:

• da + la = dalla

Here da indicates the point or opening through which something enters.

So:

• dalla valvola Presta = through/from the Presta valve

In English, through often sounds more natural here, but Italian commonly uses da with verbs of movement to show the route, opening, or point of passage.

Compare:

• entrare dalla porta = to enter through the door
• entrare dalla finestra = to come in through the window

So entra nella camera d'aria dalla valvola Presta means the air goes into the tube by way of / through the Presta valve.

Because they express two different ideas:

• nella camera d'aria = where the air goes
• dalla valvola Presta = the point it passes through

So the structure is:

• enters into the inner tube
• through the Presta valve

Italian often uses one preposition for the destination and another for the passage point:

• Il gatto entra nella stanza dalla finestra.
  • The cat enters the room through the window.

That is the same pattern as your sentence.

In Italian, descriptive words and type labels often come after the noun.

So:

• valvola Presta = Presta valve

This is similar to other Italian patterns where the main noun comes first and the specification follows it.

Also, Presta here is not acting like a normal adjective such as grande or piccola. It is the name of a type of valve, so it stays unchanged.

Because Presta is identifying the type of valve, not introducing a separate noun that needs its own article.

The article already belongs to valvola:

• dalla valvola Presta

This works much like a classification label:

• la valvola Schrader
• la valvola Presta

You would not normally say la valvola la Presta.

You might hear dentro, but nella is the more natural choice in this sentence.

• nella camera d'aria simply marks the destination: into the inner tube
• dentro la camera d'aria emphasizes inside

So dentro is possible in some contexts, but entrare nella... is the standard and smooth phrasing.

For example:

• L'aria entra nella camera d'aria. = normal, neutral
• L'aria va dentro la camera d'aria. = possible, but less elegant here

Yes, Italian word order is flexible, although the original sentence is clear and natural.

The standard order here is:

• subject + verb + destination + passage point

So:

• L'aria entra nella camera d'aria dalla valvola Presta.

But you could move parts around for emphasis, for example:

• Dalla valvola Presta, l'aria entra nella camera d'aria.

This gives more emphasis to through the Presta valve.

Even though Italian allows this flexibility, the original version is probably the best neutral sentence for a learner to remember.