Ég les glósurnar aftur áður en prófið byrjar.

Les is the present tense form of the verb að lesa (to read).

• að lesa = the infinitive, to read
• ég les = I read / I am reading

So in a full sentence with ég (I), you need the finite verb form les, not the infinitive lesa.

A quick comparison:

• Ég les. = I read / I am reading
• Mig langar að lesa. = I want to read

After a subject like ég, Icelandic normally uses the conjugated verb form.

Glósurnar means the notes.

It comes from the noun glósa (note, often a study note or annotation). Here it appears as definite plural:

• glósa = a note
• glósur = notes
• glósurnar = the notes

The ending -nar is the definite article attached to the noun in the plural.

In this sentence, glósurnar is the direct object of les (read), so it is in the case required by the verb. For this noun, the form glósurnar is the normal definite plural object form.

Not quite. Glósa usually refers to study notes, annotations, glosses, or written notes connected to learning/texts.

So glósurnar in this sentence most naturally means something like:

• the notes
• the study notes
• the class notes

Nóta can also mean note, but glósa often feels especially appropriate in an academic or studying context.

Here aftur means again.

So:

• Ég les glósurnar aftur = I read the notes again

Depending on context, aftur can also mean back, but in this sentence again is the natural meaning.

Examples:

• Hann kemur aftur. = He comes back / He returns
• Ég reyni aftur. = I try again

That word order is very natural in Icelandic.

In a simple main clause, Icelandic often puts things in an order like:

subject + verb + object + adverb

So:

• Ég = subject
• les = verb
• glósurnar = object
• aftur = adverb

That gives:

Ég les glósurnar aftur.

You may sometimes see adverbs in other positions too, but this placement is completely normal and idiomatic.

Áður en means before when it introduces a clause.

It is a fixed expression made up of:

• áður = earlier / before
• en = than / when used in certain conjunction-like structures

Together, áður en functions like a conjunction:

• áður en prófið byrjar = before the exam starts

So even though English uses one word, Icelandic uses this two-word expression.

Prófið means the exam or the test.

It comes from próf:

• próf = exam, test
• prófið = the exam / the test

The noun próf is neuter, and the definite article is attached to the end of the noun. So -ið here is the definite ending.

In this clause, prófið is the subject of byrjar.

Byrjar is the present tense, 3rd person singular form of að byrja (to begin / to start).

Since the subject is prófið (the exam), Icelandic uses the 3rd person singular verb form:

• prófið byrjar = the exam starts

Compare:

• ég byrja = I begin
• þú byrjar = you begin
• prófið byrjar = the exam begins

That is a very good question, because Icelandic is often described as a verb-second language.

In the main clause, verb-second applies:

• Ég les glósurnar aftur ...

But after a subordinating expression like áður en, you are in a subordinate clause, and the word order is different. In that clause, subject + verb is normal:

• áður en prófið byrjar

So this is expected:

• main clause: Ég les ...
• subordinate clause: áður en prófið byrjar

Yes.

Even though les and byrjar are both present-tense forms, the sentence can refer to something happening before a future event. Icelandic, like English, often uses the present tense for:

• scheduled events
• near-future actions
• events understood from context

So prófið byrjar can mean the exam starts in a future sense, just like English says:

• before the exam starts

rather than necessarily before the exam will start.

Yes, but it changes the nuance.

• Ég les glósurnar aftur áður en prófið byrjar.

  • simple present
  • can sound like a general plan, habit, or straightforward statement

• Ég er að lesa glósurnar aftur áður en prófið byrjar.

  • literally I am reading the notes again before the exam starts
  • emphasizes the action as ongoing right now

So the original sentence is often the more neutral and natural way to express the idea unless you specifically want to stress that the reading is in progress at this moment.

Because Icelandic usually puts the definite article onto the noun itself as an ending.

That is why you get forms like:

• glósurnar = the notes
• prófið = the exam

Instead of a separate word like English the, Icelandic commonly attaches definiteness directly to the noun.

Very roughly:

• glósur = notes
• glósurnar = the notes
• próf = exam
• prófið = the exam

This is one of the most important patterns to get used to in Icelandic.