Maandag werk ik thuis.

Because Dutch main clauses usually follow the verb-second rule.

If you start the sentence with Maandag, then the finite verb must come next:

• Maandag werk ik thuis.

So the order is:

• Maandag = time expression
• werk = finite verb
• ik = subject
• thuis = rest of the sentence

If you start with the subject instead, you get:

• Ik werk maandag thuis.

That is also correct.

Yes, absolutely.

Both of these are correct:

• Maandag werk ik thuis.
• Ik werk maandag thuis.

The difference is mainly focus:

• Maandag werk ik thuis. puts Monday first, so it highlights the day.
• Ik werk maandag thuis. is a more neutral word order.

In Dutch, you normally do not use a preposition before days of the week when they are used like this.

So English says:

• on Monday

but Dutch usually just says:

• maandag

Examples:

• Ik werk maandag. = I work on Monday.
• We zien elkaar vrijdag. = We’ll see each other on Friday.

Werken is the infinitive, meaning to work.

In the sentence, the verb has to be conjugated for ik in the present tense:

• ik werk
• jij werkt
• hij/zij werkt
• wij werken

So:

• Maandag werk ik thuis.

uses werk because the subject is ik.

Thuis means at home.

It is very commonly used as an adverb, not as a noun phrase.

So Dutch says:

• Ik werk thuis. = I work at home / I work from home.

This is more natural than trying to translate English word-for-word.

A useful contrast:

• thuis = at home
• in huis = in the house

So thuis is about being at home, while in huis is more literally about being inside the house.

That is a very natural place for it in Dutch.

Dutch word order in a simple main clause often puts information like place later in the sentence:

• Ik werk thuis.
• Maandag werk ik thuis.

Here, thuis gives the location, and sentence-final position sounds very normal.

Dutch word order can be somewhat flexible, but this version is one of the most natural ways to say it.

No.

In Dutch, days of the week are normally written with a lowercase letter:

• maandag
• dinsdag
• woensdag

It is capitalized here only because it is the first word of the sentence:

• Maandag werk ik thuis.

If it appears later, it is lowercase:

• Ik werk maandag thuis.

It can mean either, depending on context.

Dutch present tense often covers both:

• a habitual meaning: I work at home on Mondays
• a scheduled/future meaning: I’m working from home on Monday

If the situation is not clear, context usually tells you which meaning is intended.

Yes, but it changes the emphasis.

Because Dutch allows different elements to come first, you can front thuis:

• Thuis werk ik maandag.

This is grammatical, but it sounds more marked, as if you are emphasizing at home.

For example, it might imply contrast:

• Thuis werk ik maandag, maar dinsdag ga ik naar kantoor.

For a neutral sentence, Maandag werk ik thuis or Ik werk maandag thuis is more common.

Thuis is pronounced roughly like thouse, but not exactly.

A simple approximation for English speakers is:

• th-owss or t-house with one syllable

The ui sound is one of the trickier Dutch vowels, so learners often need practice with it.

Also:

• Maandag sounds roughly like MAHN-dakh
• werk has a short e, somewhat like the vowel in bed, but with a Dutch r
• ik is short, like ick

It is neutral and works in both formal and informal situations.

There is nothing especially casual or especially formal about:

• Maandag werk ik thuis.

You could use it in everyday speech, in an email, or in a work context.