Väggen är redan målad.

Because väggen is the definite singular form of vägg, an en-word.

• en vägg = a wall
• väggen = the wall

In Swedish, the definite article is usually added as an ending, not written as a separate word like English the.

Here, är is used because målad describes the state of the wall: it is already in a painted condition.

So Väggen är redan målad means something like:

• The wall is already painted
• The wall has already been painted in the sense that the result is now true

If you used har, you would normally be talking more directly about the completed action:

• Väggen har redan målats = The wall has already been painted

That version sounds more like an event/process.
Är ... målad focuses more on the result.

Målad is the past participle of the verb måla = to paint.

Here it behaves like an adjective and agrees with the noun.

Compare:

• Väggen är målad = the wall is painted
• Huset är målat = the house is painted
• Väggarna är målade = the walls are painted

So it comes from a verb, but in this sentence it functions adjectivally.

Because väggen is:

• singular
• common gender (en-word)

Swedish past participles/adjectives often agree like this:

• en-word singular → målad
• ett-word singular → målat
• plural → målade

Examples:

• en vägg → väggen är målad
• ett hus → huset är målat
• flera väggar → väggarna är målade

That is a very natural position for adverbs like redan in Swedish.

So:

• Väggen är redan målad

is the normal word order.

Swedish often places sentence adverbs after the finite verb in main clauses.
Here:

• Väggen = subject
• är = finite verb
• redan = adverb
• målad = complement

You may see other placements in special contexts, but this is the standard one.

Not exactly in the same way as a true passive verb form.

Väggen är redan målad uses är + participle and describes a resulting state.

A more clearly verbal passive would be:

• Väggen målas = The wall is being painted / gets painted
• Väggen målades = The wall was painted
• Väggen har målats = The wall has been painted

So är målad is often best understood as state/result, not just as a plain passive event.

Yes. That is also correct, but it has a slightly different feel.

• Väggen är redan målad → focuses on the wall’s current condition
• Väggen har redan målats → focuses more on the completed action

In many everyday situations, both could work.
If you want to emphasize that the wall now stands finished, är redan målad is very natural.

It can be at the beginning, but then Swedish word order changes because of the verb-second rule.

Normal version:

• Väggen är redan målad

You can also say:

• Redan är väggen målad

But that sounds marked or literary in many contexts.

A more natural sentence-fronting option would usually be used only for emphasis, and Swedish still keeps the finite verb in second position. So the original sentence is the neutral, everyday form.

Then the participle changes form.

Example with ett hus:

• Huset är redan målat = The house is already painted

Notice:

• väggen → målad
• huset → målat

That is because hus is an ett-word.

You would use plural forms:

• Väggarna är redan målade

Changes:

• väggen → väggarna = the wall → the walls
• målad → målade for plural agreement

So the participle agrees in number as well as gender.

It can describe many things that have been painted.

For example:

• Dörren är målad = The door is painted
• Huset är målat = The house is painted
• Stolarna är målade = The chairs are painted

So målad / målat / målade works broadly as the participle of måla.

A rough guide:

• ä is somewhat like the vowel in English bed, though not exactly the same
• gg means the consonant is short and the preceding vowel is also short
• väggen is approximately VEG-en, but with a Swedish ä

Also, the ending -en is usually unstressed.

So the word is not pronounced like English vague-gen; it has a shorter vowel and a tighter consonant.

Yes. Like English painted, it can be general.

Depending on context, it may simply mean that the object has been painted, or it may imply a finished painted surface or color treatment.

If you want to specify a color, Swedish often adds it:

• Väggen är målad blå = The wall is painted blue

So målad by itself just tells you the painting has been done.