Barnið leikur sér stundum í baðkarinu, en sápan fer ekki í handlaugina.

Barn means child in the indefinite sense, while barnið means the child.

Icelandic usually adds the definite article to the end of the noun instead of using a separate word like English the. So:

• barn = a child / child
• barnið = the child

Also, barn is a neuter noun, so it takes neuter endings even if the child is a boy or a girl. That is grammatical gender, not biological sex.

Because Icelandic very often expresses the as a suffix attached to the noun.

In this sentence:

• barnið = the child
• sápan = the soap
• baðkarinu = the bathtub in a dative form
• handlaugina = the sink in an accusative form

So instead of a separate article before the noun, Icelandic usually builds definiteness into the noun itself.

Because leika sér is the normal Icelandic expression for to play in the sense of have fun / amuse oneself.

So:

• barnið leikur sér = the child is playing

By contrast, leika without sér often has a more direct object or another specific meaning, such as play a role, play a game, or perform something.

For an English speaker, it helps to learn leika sér as a set expression.

Sér is a reflexive pronoun. In this sentence it refers back to the subject, barnið.

So leika sér literally has the sense of play oneself, although that is not how we translate it naturally into English. In normal English, we simply say play.

Grammatically, sér is the dative form of the reflexive pronoun, because the expression leika sér requires dative.

Leikur is the 3rd person singular present tense of leika.

That matches the subject barnið, which is singular:

• barnið leikur sér = the child plays / is playing

So the ending -ur here is part of the present-tense verb form.

This is one of the most important Icelandic case patterns.

With í:

• dative usually means location: in
• accusative usually means movement into: into

So here:

• í baðkarinu = in the bathtub → location, so dative
• í handlaugina = into the sink → movement/direction, so accusative

That is why the two noun forms are different.

A useful comparison:

• Sápan er í handlauginni = The soap is in the sink.
• Sápan fer í handlaugina = The soap goes into the sink.

Baðkarinu is the dative singular definite form of baðkar.

So it tells you several things at once:

• the noun is singular
• it is definite = the bathtub
• it is in the dative case

That dative is used because í takes dative when it expresses location.

Handlaugina is the accusative singular definite form of handlaug.

So it means:

• the sink
• singular
• definite
• accusative case

It is accusative because í is showing movement or direction here: into the sink.

In a normal Icelandic main clause, the finite verb usually comes early in the sentence, and ekki normally follows that finite verb.

So:

• sápan fer ekki í handlaugina

This is the usual neutral order.

This fits the broader Icelandic V2 pattern, where the finite verb tends to come in the second slot of the clause.

Stundum means sometimes, and adverbs like this are fairly flexible, but not completely free.

The sentence gives a very natural neutral order:

• Barnið leikur sér stundum í baðkarinu.

You can also put stundum first for emphasis or style:

• Stundum leikur barnið sér í baðkarinu.

Notice that when stundum comes first, the verb leikur still comes before the subject barnið. That is again the Icelandic V2 pattern.

Sápan is the nominative singular definite form of sápa.

So:

• sápa = soap
• sápan = the soap

It is nominative because sápan is the subject of the second clause: the soap does not go into the sink.

This is a good reminder that the definite ending is not always the same on every noun; it changes depending on gender, number, and case.

Yes, fer is from fara, which often means go. Here it means that the soap goes / moves / ends up into the sink.

In natural English, depending on context, you might translate it as:

• doesn’t go into the sink
• doesn’t end up in the sink
• doesn’t get into the sink

So the Icelandic verb is straightforward, but English may choose a slightly different natural phrasing.