Ég set lyklana á snagann í ganginum svo ég týni þeim ekki aftur.

Yes:

• Ég = I
• set = put / place
• lyklana = the keys
• á = on / onto
• snagann = the hook / peg
• í = in
• ganginum = the hallway / corridor
• svo = so that
• ég = I
• týni = lose / misplace
• þeim = them
• ekki = not
• aftur = again

A very natural full translation is:

I put the keys on the hook in the hallway so I don’t lose them again.

Setja is the infinitive, meaning to put / to place.
In the sentence, the verb is conjugated for 1st person singular present tense:

• að setja = to put
• ég set = I put / I place

So Ég set simply means I put or I place.

This present tense can describe a habitual action, so the sentence sounds like something the speaker regularly does: I put the keys...

Because lyklana means the keys and is the form needed here as the direct object of set.

The basic noun is:

• lykill = key

Here it is:

• plural: because we mean more than one key
• definite: the keys, not just keys
• in the accusative: because it is the direct object of setja

So:

• lyklana = the keys

A native English speaker often expects a separate word for the, but in Icelandic the definite article is usually attached to the noun as an ending.

This is a very common Icelandic pattern: many prepositions change case depending on whether you mean movement toward a place or location in a place.

Here:

• á snagann = onto the hook

  • this shows movement toward a destination
  • so á takes the accusative

• í ganginum = in the hallway

  • this shows location, not movement
  • so í takes the dative

So the contrast is:

• movement/change of position → often accusative
• static location → often dative

That is exactly why the sentence has:

• á snagann
• í ganginum

Snagi means a hook, peg, or coat hook—something you hang things on.

So á snagann means on the hook or more naturally onto the hook.

In this sentence, it is the place where the speaker puts the keys so they will be easy to find.

Here svo means so that or in order that.

It introduces the purpose of the action:

• Ég set lyklana á snagann í ganginum = I put the keys on the hook in the hallway
• svo ég týni þeim ekki aftur = so that I don’t lose them again

So svo is not being used here as so / then in the conversational sense. It is introducing a purpose clause.

Because pronouns also change form depending on case.

In the first clause, lyklana is the object of set, so it appears in the case that verb requires there.

In the second clause, the verb týna takes a dative object, so them must appear in the dative plural form:

• þeim = them (dative plural)

So even though lyklana and þeim refer to the same thing, they do not stay in the same form, because their grammatical role changes.

This is very normal in Icelandic.

Yes—this is one of those verbs that learners simply need to remember.

You týna einhverju = lose / misplace something

So you get forms like:

• Ég týndi lyklunum. = I lost the keys.
• Ég týni þeim ekki aftur. = I won’t lose them again.

This is an important point because English does not show case this way, but Icelandic does. With many Icelandic verbs, part of learning the verb is learning which case it governs.

Many learners ask this because after svo meaning so that, Icelandic often uses the subjunctive in a purpose clause.

So in a sentence like this, týni is the expected form after svo. At the same time, for learners, it may look identical to the ordinary present ég týni, so there is no big visible contrast here.

The most useful practical takeaway is:

• after svo meaning so that, expect the kind of verb form used in purpose clauses
• here that form is týni

If you are still early in Icelandic, it is enough to understand the whole chunk svo ég týni þeim ekki aftur as so that I don’t lose them again.

This is normal Icelandic word order.

In the subordinate clause:

• ég = subject
• týni = verb
• þeim = object pronoun
• ekki = not
• aftur = again

So:

• svo ég týni þeim ekki aftur

Two things are worth noticing:

1. Ekki usually comes after the finite verb.
2. Short object pronouns like þeim often appear before ekki.

And aftur at the end gives the sense again:

• ekki aftur = not again

So the meaning is specifically: so I don’t lose them again.

Because Icelandic usually puts the definite article onto the end of the noun instead of using a separate word like English the.

In this sentence:

• lyklana = the keys
• snagann = the hook
• ganginum = the hallway

The endings are not all the same because Icelandic nouns change according to:

• gender
• number
• case

So the definite form is not one single ending. It changes with the grammar of the noun.

That is why English speakers often feel that Icelandic nouns are doing several jobs at once: the form tells you not only the noun itself, but also the, singular/plural, and case.