Ég drekk ekki kaffi heldur te.

In Icelandic, the negation word ekki usually comes after the finite verb in a normal main clause.

So:

• Ég drekk ekki ...
• literally: I drink not ...

This is normal Icelandic word order, even though English says I do not drink ...

A very useful pattern is:

• subject + verb + ekki + rest

So this sentence follows standard Icelandic syntax.

Drekk is the 1st person singular present tense form of the verb drekka, meaning to drink.

So:

• ég drekk = I drink
• að drekka = to drink

A learner may notice that drekka changes its vowel in the present tense:

• infinitive: drekka
• present, ég form: drekk

This kind of stem change is common in Icelandic verbs.

Here, heldur means something like but rather or instead.

In this sentence, it appears in the very common pattern:

• ekki X heldur Y

which means:

• not X but Y
• or more literally, not X but rather Y

So:

• ekki kaffi heldur te = not coffee but tea

This use of heldur is extremely common, and it is best learned as part of the whole pattern rather than as a standalone word.

Because Icelandic often uses the fixed contrast pattern:

• ekki ... heldur ...

rather than simply using en for this kind of correction or replacement.

Compare the idea:

• not coffee, but tea

In Icelandic, that is very naturally expressed as:

• ekki kaffi heldur te

So although en can mean but in other contexts, this sentence specifically uses the standard not X but Y construction.

Icelandic does not have an indefinite article like English a/an.

So:

• kaffi can mean coffee
• te can mean tea

When speaking generally, Icelandic often uses the bare noun with no article.

If you wanted the definite form, you would use forms like:

• kaffið = the coffee
• teið = the tea

But in this sentence, the speaker means coffee and tea in a general sense, so the bare nouns are the natural choice.

They are the objects of the verb drekka, so they are in the accusative case.

However, in this sentence, that is not very obvious from the spelling, because these nouns do not change form here.

For these words:

• kaffi looks the same in nominative and accusative singular
• te also looks the same in nominative and accusative singular

So even though the case is accusative, the form stays unchanged.

Because Icelandic does not use do-support the way English does.

English says:

• I do not drink coffee

But Icelandic simply negates the main verb directly:

• Ég drekk ekki kaffi

So there is no extra helping verb equivalent to English do in this sentence.

Yes — the pattern is very worth memorizing:

• ekki X heldur Y

It is a very common and useful structure for correcting, contrasting, or replacing one thing with another.

You can use it in many situations, for example:

• Ég borða ekki kjöt heldur fisk.
  I eat not meat but fish.
• Hún les ekki bækur heldur blöð.
  She reads not books but magazines/newspapers.

Learning the whole pattern will help you sound much more natural.

Ég means I, and the accent mark shows that the vowel is pronounced differently from plain e.

The é in Icelandic is pronounced roughly like ye at the start of the word, so Ég is approximately like yeg.

The accent marks in Icelandic are important: they are not optional decoration, but part of the spelling and pronunciation of the word.

So you should learn Ég with the accent included.

Yes, you may sometimes see punctuation used for clarity, especially in writing:

• Ég drekk ekki kaffi, heldur te.

But the sentence is also perfectly normal without the comma:

• Ég drekk ekki kaffi heldur te.

The main thing to recognize is the structure ekki ... heldur ..., not the punctuation.

By itself, it usually sounds like a general statement or preference:

• I don’t drink coffee, but tea

That is because the present tense in Icelandic, like in English, can often express a general habit or usual behavior.

Context decides the exact meaning. In the right situation, it could also refer to what the speaker is drinking now, but most naturally it sounds like a general preference or habit.