Learn Hardcore Icelandic: Hún bætir íslenskuna sína á hverjum degi með litlum æfingum. - She improves her Icelandic every day with small exercises.

Object case (accusative)
The verb bæta (to improve) takes a direct object. Direct objects are in the accusative case.
- Base form (nominative, indefinite): íslenska (Icelandic, the language)
- Accusative, definite: íslenskuna
So you need the accusative because it’s the thing being improved.
Definite form (“the Icelandic”)
In Icelandic, when you say my X, your X, her X, etc., the noun is normally in the definite form:
- íslenska = Icelandic (language), in general
- íslenskan / íslenskuna = the Icelandic (here, her Icelandic)
With a possessive pronoun (sína), you typically use the definite noun:
- íslenskuna sína ≈ her Icelandic (ability/knowledge)

What exactly does sína mean here, and how is it different from hennar?

Sína is the reflexive possessive pronoun: it refers back to the subject of the same clause.

Hún bætir íslenskuna sína.
= She improves *her own Icelandic.*
Hún bætir íslenskuna hennar.
= She improves *her Icelandic (some other woman’s).*

So:

Use sinn / sín / sitt / sínir / sínar / sín when the owner is the subject.
Use hennar (her), hans (his) when the owner is someone else, not the subject.

In the sentence, the subject is Hún, and it is her own Icelandic she is improving, so sína is correct.

What case is íslenskuna sína, and how can I recognize it?

Íslenskuna sína is in the accusative singular feminine.

Why?

It is the direct object of bætir. Verbs like bæta take their object in the accusative.
Íslenska (language) is a feminine noun.

Declension of íslenska (singular, indefinite vs. definite):

Nominative:
- indefinite: íslenska
- definite: íslenskan
Accusative:
- indefinite: íslensku
- definite: íslenskuna

In our sentence, we need:

accusative (object)
definite (with a possessive)

→ íslenskuna.

Sína agrees with íslenskuna:

feminine
singular
accusative

So the whole phrase íslenskuna sína is accusative singular feminine.

What is the base form (infinitive) of bætir, and how is it conjugated?

The infinitive is bæta (to improve, to add).

Present tense (indicative):

ég bæti – I improve
þú bætir – you (sing.) improve
hann / hún / það bætir – he / she / it improves
við bætum – we improve
þið bætið – you (pl.) improve
þeir / þær / þau bæta – they improve

In the sentence:

Subject: Hún (she)
Verb form: bætir (3rd person singular present)

So Hún bætir = She improves.

Why is it á hverjum degi instead of something like á hver dag?

Two reasons:

The preposition á with time can take the dative
When á is used in a temporal sense meaning “every …”, you get the dative:
- á hverjum degi = on each day → every day
Hverjum and degi are both dative singular masculine
- dagur (day) is masculine:
  - nominative: dagur
  - accusative: dag
  - dative: degi
- hver (each, every), masculine dative singular: hverjum

So á + hverjum degi is a fixed, natural way to say on every day / every day.

What case are hverjum and degi in, and how do their forms work?

Both hverjum and degi are dative singular masculine.

Noun dagur (day):
- nom. sg.: dagur
- acc. sg.: dag
- dat. sg.: degi
- gen. sg.: dags
Determiner hver (each, every), masculine singular:
- nom.: hver
- acc.: hvern
- dat.: hverjum
- gen.: hvers

Because the preposition á (in this time expression) requires dative, both words appear in the dative:

hverjum degi = (on) each day

What does með litlum æfingum literally mean, and what case is used there?

Með litlum æfingum literally means “with small exercises” or “by means of small exercises”.

Case and structure:

Preposition með can take accusative or dative, depending on meaning.
- Dative is used for accompaniment / instrument (with, by means of).
  Here it’s instrumental: by doing small exercises → dative.
Noun æfing (exercise) is feminine:
- nom. pl.: æfingar
- acc. pl.: æfingar
- dat. pl.: æfingum
- gen. pl.: æfinga
Adjective lítill (small), dative plural (all genders): litlum

So:

æfingum = dative plural of æfing
litlum = dative plural of lítill, agreeing with æfingum

Whole phrase: með + litlum æfingum (prep + dative plural) = with small exercises.

Does litlum æfingum mean “small exercises” or “short / simple exercises”? Could you use something else?

Literally, litlum æfingum is “small exercises” (small in size or scope), but in context it can easily be understood as short or simple exercises.

Subtleties:

lítill = small (size, amount), often also used loosely for simple or not very big tasks.
If you specifically mean short (in time/length), stuttur is more precise:
- með stuttum æfingum = with short exercises
For small / minor in a more abstract sense, smár or lítilvægur can appear, but lítill is the most common, neutral word you’ll see.

In everyday usage, litlum æfingum sounds natural and is usually understood as small/simple, low‑effort exercises.

Can the word order be changed, for example putting á hverjum degi at the start of the sentence?

Yes, Icelandic word order is fairly flexible, as long as the verb stays in second position in main clauses (the V2 rule).

Some possible variants:

Á hverjum degi bætir hún íslenskuna sína með litlum æfingum.
Every day she improves her Icelandic with small exercises.
Hún bætir á hverjum degi íslenskuna sína með litlum æfingum.
Hún bætir íslenskuna sína með litlum æfingum á hverjum degi.

All of these are grammatical. The differences are mainly in emphasis:

Fronting Á hverjum degi emphasizes the frequency.
Putting með litlum æfingum earlier would emphasize the method.

But you must keep the finite verb (bætir) in second position in a main clause:

Á hverjum degi bætir hún … (OK)
Á hverjum degi hún bætir … (wrong in Icelandic)

Is there a shorter or more idiomatic way in Icelandic to say “every day” or “improves her Icelandic” in this context?

Yes, there are a couple of common alternatives:

Instead of á hverjum degi, you can say:
- daglega = daily / every day
  → Hún bætir íslenskuna sína daglega með litlum æfingum.
Instead of bætir íslenskuna sína, you might also see:
- bætir sig í íslensku = literally “improves herself in Icelandic”
  → Hún bætir sig í íslensku á hverjum degi með litlum æfingum.

Original sentence is perfectly natural, but these are very common alternative patterns you’ll encounter.

What are the genders of íslenska, dagur, and æfing, and why do they matter for the endings?

íslenska (Icelandic, language) → feminine
This is why you see:
- definite accusative sg.: íslenskuna
- matching feminine accusative sg. of the reflexive: sína
dagur (day) → masculine
Hence:
- dative sg.: degi
- hver matches in masculine dative sg.: hverjum degi
æfing (exercise) → feminine
So the dative plural is:
- æfingum
- adjective lítill agrees in dative plural: litlum æfingum

In Icelandic, gender + case + number control most of the endings on nouns, adjectives, and pronouns, so knowing the gender of each noun is crucial for getting forms like íslenskuna sína, á hverjum degi, and með litlum æfingum right.