Brödet har mögel och är mögligt.

Because brödet is the definite form of bröd.

• ett bröd = a bread / a loaf of bread
• brödet = the bread

Swedish often attaches the definite article to the end of the noun instead of using a separate word like the.

So:

• Brödet har mögel = The bread has mold

Because mögel is a noun, not an adjective.

• mögel = mold
• möglig / mögligt = moldy

So har mögel means has mold. That is the natural way to express that mold is present on something.

If you said är mögel, it would mean is mold, as if the bread itself were literally mold, which is not what you want.

They are different parts of speech:

• mögel = a noun = mold
• möglig / mögligt = an adjective = moldy

So in this sentence:

• Brödet har mögel = the bread has mold
• Brödet är mögligt = the bread is moldy

The sentence uses both a noun phrase and an adjective to describe the same situation.

Because bröd is an ett-word, and Swedish adjectives often change form to agree with the noun.

Here is the pattern:

• en-word: möglig
• ett-word: mögligt
• plural / definite: mögliga

Since bröd is ett bröd, the adjective becomes mögligt:

• Brödet är mögligt

This is called adjective agreement.

Because mögel is usually treated like an uncountable noun here, similar to English mold.

Compare:

• Brödet har mögel = The bread has mold
• not usually The bread has a mold in this meaning

So Swedish does not use an article here, just as English normally does not.

Because the subject is the same in both parts of the sentence, and Swedish often leaves it out in the second part when it is easy to understand.

So:

• Brödet har mögel och är mögligt

means the same as the more repetitive:

• Brödet har mögel och brödet är mögligt

The shorter version sounds much more natural.

This works because both verbs refer to the same subject, brödet.

Yes, a little.

If bread has mold, it is usually already clear that it is moldy. So saying both can sound slightly repetitive, but it is still perfectly understandable.

A speaker might use both for emphasis or clarity.

More compact alternatives would be:

• Brödet är mögligt = The bread is moldy
• Det är mögel på brödet = There is mold on the bread

Yes. That is very natural.

In many situations, Brödet är mögligt is enough by itself. It directly describes the condition of the bread.

Using har mögel is also possible, but är mögligt often sounds a bit more straightforward when you simply want to say the bread is no longer good.

No. Möglig can be used for many things that have mold on them, for example:

• mögligt bröd = moldy bread
• möglig ost = moldy cheese
• en möglig vägg = a moldy wall
• mögliga kläder = moldy clothes

So it is a general adjective meaning covered with mold or affected by mold.

This is a very common Swedish pattern:

• är = is
• mögligt = adjective describing the subject

So mögligt is a predicative adjective. It comes after är and describes brödet.

Compare:

• Brödet är gott = The bread is good
• Brödet är gammalt = The bread is old
• Brödet är mögligt = The bread is moldy

The adjective changes form to match the noun, which is why you see mögligt rather than möglig.