Svona mistök eru algeng þegar fólk byrjar að læra nýtt tungumál.

Here svona means something like such, like this, or of this kind.

So Svona mistök means:

• mistakes like this
• this kind of mistakes
• more naturally in English, such mistakes

A useful thing to know is that svona is very flexible in Icelandic. In other contexts it can also mean like this or this way.

Yes, mistök is plural here.

In fact, mistök is very often treated as a plural-only noun in Icelandic, meaning mistake/mistakes depending on context. In this sentence, it is clearly plural because:

• the verb is eru = are
• the adjective is algeng = plural agreement here

So the sentence is talking about mistakes in general, not one single mistake.

Because the subject, mistök, is plural.

• er = is for singular
• eru = are for plural

So:

• Mistökin eru algeng = The mistakes are common
• Mistakið er algengt = The mistake is common

In your sentence, the subject is plural, so eru is required.

Because adjectives in Icelandic agree with the noun they describe in gender, number, and often case.

Here the noun is mistök, which is:

• neuter
• plural
• nominative here, because it is the subject

So the adjective has to match that. The correct form is algeng.

Compare:

• algengur = masculine singular
• algeng = feminine singular or neuter plural, depending on context
• algengt = neuter singular

Since mistök is neuter plural, algeng is the right form.

Because fólk is grammatically singular in Icelandic, even though it often means people.

So Icelandic treats it like a singular collective noun:

• fólk byrjar = people start
• not fólk byrja

This is different from English, where people is grammatically plural. A good way to think of fólk is as something closer to people as a group.

Þegar means when here.

It introduces a subordinate clause:

• þegar fólk byrjar að læra nýtt tungumál
• when people start to learn a new language

Yes, the word order is normal. Icelandic does not push the verb to the end the way German does.

So this is completely natural:

• þegar fólk byrjar...

You can also move this clause to the front:

• Þegar fólk byrjar að læra nýtt tungumál, eru svona mistök algeng.

Then the main clause changes word order because Icelandic main clauses follow the V2 pattern.

Because að + infinitive is the normal way to express to do something after many verbs.

Here:

• byrjar = starts
• að læra = to learn

So byrjar að læra means starts to learn.

This is a very common pattern in Icelandic:

• ætla að fara = intend to go
• reyna að skilja = try to understand
• byrja að læra = start to learn

Because tungumál is a neuter singular noun, and nýtt is the neuter singular form of nýr = new.

So the adjective agrees with the noun:

• nýr = masculine singular
• ný = feminine singular
• nýtt = neuter singular

Since tungumál is neuter singular, you get nýtt tungumál.

It is in the accusative, because it is the direct object of að læra.

You are learning a new language, so nýtt tungumál is the thing being learned.

However, you do not see a visible change here, because for many neuter nouns and adjectives, the nominative and accusative forms look the same.

So even though it is accusative, it still appears as:

• nýtt tungumál

Because Icelandic has no indefinite article.

English says:

• a new language

Icelandic simply says:

• nýtt tungumál

So a bare noun can mean a/an in English, depending on context.

If you want the, Icelandic usually adds a definite article to the noun:

• tungumálið = the language

So:

• nýtt tungumál = a new language
• nýja tungumálið = the new language

Yes. That is a very natural way to understand it.

Depending on context, svona mistök can mean:

• such mistakes
• mistakes like this
• this kind of mistake/mistakes

So the exact English wording may vary, but the Icelandic idea is the same: these are the kinds of mistakes that commonly happen when someone starts learning a new language.