Någon försökte stjäla värdesakerna.

Någon means someone here and is the subject of the sentence — the person who did the action.

A few useful points:

• någon is a common-indefinite word meaning someone / somebody
• it can also mean anyone in some contexts, especially in questions or negatives
• here, in a normal statement, it is understood as someone

So the structure begins with someone tried...

Försökte is the past tense of the verb försöka, which means to try.

• försöka = to try
• försöker = tries / is trying
• försökte = tried
• försökt = tried (supine/past participle-related form, depending on use)

Since the sentence describes something that happened in the past, Swedish uses försökte.

Because after försöka in Swedish, the next verb normally stays in the infinitive.

So:

• försöka stjäla = to try to steal
• försökte stjäla = tried to steal

This works much like English, except Swedish often does not use a separate word for to in this pattern.

After försöka, Swedish normally uses the infinitive without att.

So Swedish says:

• försökte stjäla

not:

• försökte att stjäla

In English, we say tried to steal, but in Swedish the att is usually omitted after försöka.

This is a very common pattern, so it is worth memorizing:

• försöka göra
• försöka förstå
• försöka stjäla

Stjäla means to steal.

It refers to taking something that belongs to someone else.

A useful distinction for English speakers:

• stjäla = to steal something
• råna = to rob a person / bank / store

So in this sentence, the focus is on the stolen items, not on robbing a person directly.

Värdesakerna is the definite plural form of värdesaker.

• värdesak = valuable item
• värdesaker = valuable items / valuables
• värdesakerna = the valuable items / the valuables

The ending -na marks definite plural, so it means the valuables, not just valuables in general.

It comes from värdesak, which is a compound noun:

• värde = value
• sak = thing

So:

• värdesak = a valuable thing / valuable item
• värdesaker = valuable items
• värdesakerna = the valuable items

Swedish forms many nouns by compounding like this, so learning to spot the parts can help a lot.

This is the normal Swedish main-clause word order:

• subject: Någon
• finite verb: försökte
• infinitive verb: stjäla
• object: värdesakerna

So the pattern is basically:

Someone + tried + steal + the valuables

This is very natural Swedish word order in a plain statement.

Yes, but the sentence you have is the most neutral version.

For example, you could front another element for emphasis in a different sentence, but then Swedish follows the V2 rule: the finite verb still comes second.

In this sentence, since there is no fronted time or place phrase, the normal order is simply:

Någon försökte stjäla värdesakerna.

That is the most straightforward way to say it.

Yes. They are related, but used differently.

• någon is used with common gender nouns and also as someone
• något is used with neuter nouns and can also mean something

Examples:

• Någon försökte stjäla värdesakerna. = Someone tried to steal the valuables.
• Något hände. = Something happened.

So in your sentence, någon refers to a person: someone.

A rough pronunciation is:

VAIR-deh-sah-ker-na

But a few things matter:

• Swedish ä sounds somewhat like the e in bed, though exact pronunciation varies
• the r affects nearby sounds depending on dialect
• Swedish has vowel length and stress patterns that English speakers often need time to get used to

The main stress is usually on the first part: VÄRde...

You do not need perfect pronunciation immediately, but it helps to hear the word spoken by natives because compound nouns in Swedish often have stress patterns that are hard to guess from English habits.

Not necessarily. The verb försökte only tells you that someone tried.

So the sentence means there was an attempt to steal the valuables, but it does not tell you whether the person succeeded.

If Swedish wanted to say the valuables were actually stolen, it would use a different wording, for example with stal:

• Någon stal värdesakerna. = Someone stole the valuables.

So försökte stjäla clearly leaves the result open.