Hún gerir þetta sjálf.

Because hún is third person singular (she), and the verb has to match that subject.

The verb að gera (to do / to make) is conjugated in the present tense like this:

• ég geri — I do
• þú gerir — you do
• hann/hún/það gerir — he/she/it does
• við gerum — we do
• þið gerið — you do
• þeir/þær/þau gera — they do

So in Hún gerir þetta sjálf, gerir is the correct present-tense form for hún.

Þetta means this.

In this sentence, it is the object of the verb gerir, so it means this thing or this action/task that she is doing.

A useful thing to know is that þetta is the neuter singular form of this, and it is very commonly used when referring to:

• a thing
• an idea
• a situation
• something not specifically named

So Hún gerir þetta sjálf means she is doing this herself.

Sjálf adds emphasis and means herself.

So the sentence is not just:

• Hún gerir þetta — She does this.

but:

• Hún gerir þetta sjálf — She does this herself.

It emphasizes that she personally does it, rather than someone else doing it for her or helping her.

In Icelandic, sjálfur/sjálf/sjálft often works like English self / herself / himself / itself, especially for emphasis.

Because sjálfur changes form to match the person it refers to.

Here it refers back to hún (she), which is feminine singular, so the correct form is sjálf.

The basic nominative singular forms are:

• sjálfur — masculine
• sjálf — feminine
• sjálft — neuter

So:

• Hann gerir þetta sjálfur — He does this himself.
• Hún gerir þetta sjálf — She does this herself.
• Það gerir þetta sjálft — It does this itself.

Not exactly. In this sentence, sjálf is better understood as an intensifier: it emphasizes the subject.

It is similar to English herself in:

• She did it herself.

That is different from a truly reflexive structure where the subject does something to herself. Icelandic often uses sig for reflexive objects, for example:

• Hún sér sig — She sees herself.

But in Hún gerir þetta sjálf, sjálf is not the direct object. It is adding emphasis to hún.

Putting sjálf at the end is a very natural way to give it emphasis.

So:

• Hún gerir þetta sjálf

sounds like:

• She does this herself.

The final position helps highlight the idea that she is the one doing it.

You may also see other word orders for different emphasis, such as:

• Hún sjálf gerir þetta — She herself does this.

That sounds more strongly focused on she, while Hún gerir þetta sjálf focuses naturally on the whole idea of doing it herself.

The basic structure is:

• Hún — subject
• gerir — verb
• þetta — object
• sjálf — emphatic word referring back to the subject

So the pattern is:

Subject + Verb + Object + Intensifier

This is a very normal Icelandic sentence pattern.

Yes. The verb að gera can mean both to do and to make, depending on context.

So Hún gerir þetta sjálf could mean:

• She does this herself
• She makes this herself

Which one is intended depends on what þetta refers to.

If þetta is a task, then does is more natural. If þetta is something being created, then makes may be better.

A rough English-friendly pronunciation is:

• þetta ≈ THYET-ta

A few helpful notes:

• þ is like the th in thing
• e here is short
• the tt in Icelandic is often pronounced with a distinctive sound that is not exactly like English tt
• the stress is on the first syllable

So you should aim for something like THYET-ta, while knowing the real Icelandic pronunciation is a bit sharper than that.

A rough guide is:

Hún gerir þetta sjálf
≈ hoon YEH-rir THYET-ta syelf

Helpful notes:

• Hún: the ú is like a long oo
• gerir: the g is usually pronounced more like y before front vowels in modern Icelandic
• þetta: starts with th as in thing
• sjálf: starts with an sj sound that is not quite the same as normal English s or sh; a rough approximation is fine at first

Stress usually falls on the first syllable of each word.

Yes, but the meaning becomes less emphatic.

Compare:

• Hún gerir þetta. — She does this.
• Hún gerir þetta sjálf. — She does this herself.

Without sjálf, you simply state that she does it. With sjálf, you emphasize that she personally does it.