Hon vill tacka läraren.

Hon means she. It is the subject pronoun, so it tells you who is doing the action.

• hon = she
• han = he
• jag = I
• du = you

In Hon vill tacka läraren, hon is the person who wants to do something.

Vill means want or wants here. It is the present tense of vilja (to want).

Examples:

• Jag vill = I want
• Hon vill = She wants
• De vill = They want

A useful thing to notice is that Swedish verbs do not change for different persons the way English does. So:

• I want
• she wants
• they want

all use vill in Swedish.

After modal verbs like vill (want to), Swedish normally uses the infinitive without att.

So:

• Hon vill tacka läraren. = She wants to thank the teacher.

Compare:

• Hon försöker att tacka läraren. or often just Hon försöker tacka läraren.
• But with vill, you do not say vill att tacka.

Other common modal verbs work the same way:

• kan läsa = can read
• ska gå = will/is going to go
• måste arbeta = must work
• vill tacka = wants to thank

Tacka is the infinitive form of the verb, meaning to thank.

So:

• tacka = to thank

In this sentence, it comes after vill, so it stays in the infinitive:

• Hon vill tacka läraren.

Other examples:

• Jag vill tacka dig. = I want to thank you.
• Vi måste tacka dem. = We must thank them.

Läraren means the teacher, while en lärare means a teacher.

Swedish usually adds the definite article to the end of the noun:

• en lärare = a teacher
• läraren = the teacher

So in this sentence, it is talking about a specific teacher, not just any teacher.

This is one of the big differences from English: Swedish often puts the as an ending instead of using a separate word.

Because in Swedish, the definite article is often attached to the noun as a suffix.

So:

• bok = book
• boken = the book
• lärare = teacher
• läraren = the teacher

That is why läraren already includes the meaning of the teacher.

A separate definite word like den/det/de is used in some other situations, especially with adjectives:

• läraren = the teacher
• den snälla läraren = the kind teacher

This sentence uses the normal Swedish main-clause word order:

Subject + finite verb + infinitive + object

So:

• Hon = subject
• vill = finite verb
• tacka = infinitive
• läraren = object

This is a very common pattern in Swedish:

• Jag kan simma. = I can swim.
• De vill hjälpa oss. = They want to help us.

So Hon vill tacka läraren is structurally very straightforward.

Yes. Läraren is the direct object, because it receives the action of tacka.

You can ask:

• Who does she want to thank?
• Läraren.

So:

• Hon = subject
• vill tacka = verbal phrase
• läraren = object

The pronoun would change, but vill would stay the same.

Examples:

• Jag vill tacka läraren. = I want to thank the teacher.
• Du vill tacka läraren. = You want to thank the teacher.
• De vill tacka läraren. = They want to thank the teacher.

This is a good example of how Swedish verbs do not change according to person in the present tense.

Läraren is roughly pronounced like LAIR-ah-ren, but with Swedish sounds.

A few pronunciation points:

• ä sounds somewhat like the vowel in English air or bed, depending on accent and length.
• The stress is on the first syllable: LÄ-ra-ren.
• The r sound depends on dialect, but in many varieties it is a tapped or trilled sound, not an English r.

A learner-friendly approximation is:

• LÄ-ra-ren

By itself, läraren most directly means the teacher. In context, that teacher might of course be her teacher, but Swedish is not explicitly saying her here.

If you want to clearly say her teacher, you would usually say:

• sin lärare = her own teacher
• hennes lärare = her teacher

So:

• Hon vill tacka läraren. = She wants to thank the teacher.
• Hon vill tacka sin lärare. = She wants to thank her teacher (her own teacher).

Yes. Tacka can be used with or without an object, depending on the context.

Examples:

• Hon vill tacka. = She wants to thank someone / She wants to say thanks.
• Hon vill tacka läraren. = She wants to thank the teacher.

So in your sentence, the object läraren makes it clear who is being thanked.