Læreren snakker tydelig når vi øver på uttale.

Because læreren means the teacher, while lærer means a teacher or just teacher in a general sense.

In Norwegian, the definite article is usually attached to the end of the noun:

• en lærer = a teacher
• læreren = the teacher

So Læreren snakker tydelig ... means The teacher speaks clearly ...

They are both in the present tense.

In Norwegian, the present tense is often formed by adding -er to the verb:

• å snakke = to speak

• snakker = speak / speaks

• å øve = to practise
• øver = practise / practises

Unlike English, Norwegian does not change the verb for different persons:

• jeg snakker = I speak
• du snakker = you speak
• vi snakker = we speak

The verb form stays the same.

Here it is an adverb, because it describes how the teacher speaks.

• snakker tydelig = speaks clearly

But the same word can also be an adjective:

• en tydelig stemme = a clear voice

This is common in Norwegian: the adverb often looks like the neuter form of the adjective.

• tydelig = clear / clearly

So in this sentence, tydelig is functioning like English clearly.

Når is used for something that happens regularly, generally, or whenever.

So:

• når vi øver på uttale = when / whenever we practise pronunciation

This suggests something that happens as a repeated situation, not just one single event.

By contrast, da is usually used for a specific time in the past:

• Da vi øvde på uttale i går ... = When we practised pronunciation yesterday ...

So når is the natural choice here.

Because når introduces a subordinate clause, and in Norwegian subordinate clauses, the word order is usually:

subject + verb

So:

• når vi øver på uttale

not

• når øver vi på uttale

The second version looks like a question word order in English-style thinking, but Norwegian does not do that here.

The full sentence has:

• main clause: Læreren snakker tydelig
• subordinate clause: når vi øver på uttale

Å øve på means to practise something, especially a skill or area.

So:

• øve på uttale = practise pronunciation
• øve på norsk = practise Norwegian
• øve på en sang = practise a song

The preposition på is just the one Norwegian normally uses with øve in this sense. It will not always match the English preposition exactly, so it is best to learn øve på as a set expression.

Here, uttale is a noun meaning pronunciation.

So:

• på uttale = on pronunciation / pronunciation practice

Be careful, because uttale can also be related to the verb å uttale = to pronounce.

Examples:

• uttale = pronunciation
• å uttale et ord = to pronounce a word

In this sentence, it is clearly the noun.

Because uttale is being used as an uncountable or general concept, like English pronunciation in we practise pronunciation.

Norwegian often leaves out the article in this kind of expression:

• øve på uttale = practise pronunciation
• snakke om politikk = talk about politics
• studere språk = study language / languages

If you added an article, it would sound more specific and usually mean a particular pronunciation, not pronunciation as a skill in general.

It breaks down like this:

• Læreren = the teacher
• snakker = speaks
• tydelig = clearly
• når = when
• vi = we
• øver på uttale = practise pronunciation

So the structure is:

[main clause] + [subordinate clause]

• Læreren snakker tydelig
• når vi øver på uttale

This is very natural Norwegian word order.

A rough guide:

• æ in Læreren sounds somewhat like the vowel in English cat, but not exactly.
• ø in øver is a rounded vowel that English does not really have. You can approximate it by saying e while rounding your lips.
• å does not appear in the sentence itself, but the infinitive marker å in forms like å øve is pronounced roughly like aw in law.

A very rough pronunciation guide for the whole sentence might be:

• Læreren ≈ LAIR-er-en
• snakker ≈ SNAK-er
• tydelig ≈ TUU-de-lig / TIH-de-lig depending on accent
• når ≈ nor with a rounded vowel
• vi = vee
• øver ≈ UR-ver with rounded lips
• på = paw
• uttale ≈ UHT-ta-leh

These are only approximations, but they can help you get started.