En intresserad kund frågar om bilen.

Because kund is an en-word in Swedish. Swedish nouns have two grammatical genders in modern standard Swedish: en-words and ett-words.

So:

• en kund = an/a customer
• kunden = the customer

You simply have to learn each noun with its article. A good habit is to memorize new nouns as en kund, en bil, ett hus, not just the bare noun.

Yes. Intresserad must agree with the noun it describes.

Here, kund is:

• an en-word
• singular
• indefinite

So the adjective takes the common-gender singular form:

• en intresserad kund

Other forms are:

• ett intresserat hus = an interested house
• intresserade kunder = interested customers
• den intresserade kunden = the interested customer

So intresserad changes depending on gender, number, and whether the noun phrase is definite.

Yes. In this sentence, intresserad is simply an adjective meaning interested.

It comes historically from a participle, which is why its forms may look a bit different from some basic adjectives, but in normal grammar it behaves like an adjective:

• en intresserad kund
• ett intresserat barn
• intresserade människor

So for a learner, it is best to treat it as an adjective that agrees with the noun.

The basic form is fråga, which means to ask.

Frågar is the present tense form:

• att fråga = to ask
• frågar = ask / is asking

Examples:

• Jag frågar = I ask / I am asking
• Hon frågar = she asks / she is asking

In Swedish, the present tense is often formed with -r, and many verbs in this group have an infinitive ending in -a.

Because fråga om means to ask about.

So:

• fråga om bilen = ask about the car

If you say fråga bilen, that would sound like ask the car, as if the car were the thing being questioned. That is not the intended meaning here.

This is a very common pattern:

• fråga om priset = ask about the price
• fråga om vägen = ask about the way/directions
• fråga om bilen = ask about the car

Swedish usually makes nouns definite by adding the definite article as a suffix to the noun.

So:

• en bil = a car
• bilen = the car

That is why the car is expressed as bilen, one word.

You use den together with the noun when there is also an adjective before it:

• den röda bilen = the red car

But without an adjective, you normally just say:

• bilen

So in this sentence, om bilen is exactly what you would expect.

Because in Swedish, the usual definite article is attached to the end of the noun.

Compare:

• English: the car
• Swedish: bilen

The ending -en here is the definite marker for this noun.

This is one of the biggest structural differences from English. Instead of a separate word like the, Swedish often uses a suffix:

• kunden = the customer
• bilen = the car
• huset = the house

Yes, but this sentence uses the most basic Swedish word order: subject + verb + other information.

• En intresserad kund = subject
• frågar = verb
• om bilen = prepositional phrase

So the structure is:

• En intresserad kund frågar om bilen.

This is the normal word order for a straightforward statement.

Swedish also has the verb-second rule, which means the finite verb usually comes in the second position. If you move something else to the front, the verb still stays second:

• Om bilen frågar en intresserad kund.
  This is grammatically odd in meaning here, but it shows how word order matters.

A more natural example:

• Nu frågar en intresserad kund om bilen. = Now an interested customer is asking about the car.

Here Nu comes first, and frågar still stays in second position.

Because attributive adjectives in Swedish normally come before the noun, just like in English.

So:

• en intresserad kund
• en röd bil
• ett stort hus

This part is fairly similar to English:

• an interested customer
• a red car
• a big house

The main difference is that Swedish adjectives often change form to agree with the noun.

Yes. Swedish present tense often covers both the simple present and the present progressive that English distinguishes.

So:

• En intresserad kund frågar om bilen.

can correspond to:

• An interested customer asks about the car
• An interested customer is asking about the car

Which one sounds best in English depends on context. Swedish usually does not need a separate form for is asking.

Here, om is a preposition meaning about.

So:

• fråga om något = ask about something

But be careful: om can also mean other things in other contexts, such as if.

Examples:

• Jag frågar om bilen. = I ask about the car.
• Jag undrar om bilen är dyr. = I wonder if the car is expensive.

So the meaning of om depends on the construction.

Yes, but it means something slightly more explicit and sounds longer.

• En intresserad kund = an interested customer
• En kund som är intresserad = a customer who is interested

Both are grammatical. The version in your sentence is shorter and more natural when the adjective simply describes the noun.

So Swedish, like English, often prefers the simple adjective form when possible.