Mijn jas is grijs.

In Dutch, a possessive word like mijn already takes the place of the article. So you say:

• mijn jas = my coat
• de jas = the coat

You normally do not combine them in this kind of sentence.

Mijn is a possessive determiner. It shows ownership, like my in English.

Some related forms are:

• mijn = my
• jouw / je = your
• zijn = his
• haar = her
• ons / onze = our

So in Mijn jas is grijs, mijn tells us whose coat it is.

This is a normal Dutch main clause. Dutch usually puts the finite verb in second position.

So the structure is:

• Mijn jas = subject
• is = verb
• grijs = adjective

That gives:

• Mijn jas is grijs.

In this simple sentence, the word order is very similar to English: My coat is grey.

Is is the singular form of the verb zijn (to be) for hij/zij/het and for singular nouns like jas.

So:

• ik ben
• jij bent
• hij/zij/het is
• wij zijn
• jullie zijn
• zij zijn

Because jas is singular, you use is:

• Mijn jas is grijs.

Because grijs is used after the verb is. In Dutch, adjectives used this way are called predicative adjectives, and they usually do not take -e.

So:

• De grijze jas = the grey coat
  Here the adjective comes before the noun, so it gets -e.
• De jas is grijs = the coat is grey
  Here the adjective comes after the verb, so there is no -e.

That is why the sentence uses grijs, not grijze.

Jas is a de-word:

• de jas

You do not see de in mijn jas, because mijn replaces the article, but it is still useful to know the noun’s gender/category.

For example:

• de jas
• een jas
• mijn jas
• die jas

The ij in Dutch is a very common sound and can be tricky for English speakers. In grijs, it sounds somewhat like the vowel in English eye, though the exact Dutch sound is different.

A rough guide:

• grijs ≈ sounds a bit like grice in English, but with a Dutch r and Dutch vowel quality

The ij is treated as a single unit in Dutch spelling. You will see it in many words, such as:

• mijn
• bij
• blij

Yes. In informal speech and writing, mijn is often reduced to m’n.

So you may hear or see:

• M’n jas is grijs.

This means exactly the same thing as Mijn jas is grijs, but mijn is the full, neutral form and usually the best one to learn first.

You usually add niet after the verb phrase:

• Mijn jas is niet grijs. = My coat is not grey.

So for simple sentences with zijn + adjective, niet comes before the adjective:

• is niet grijs

Then both the noun and the verb change:

• Mijn jassen zijn grijs. = My coats are grey.

Changes:

• jas → jassen
• is → zijn

The adjective grijs stays the same here, because it is still being used after the verb.

Yes, but only when the adjective comes before the noun.

Compare:

• Mijn jas is grijs.
• Mijn grijze jas.

So:

• grijs = after is
• grijze = before jas

This is one of the most important adjective patterns in Dutch.

Not always. The basic form is grijs, but it can change for grammar reasons, especially when it comes before a noun:

• een grijze jas
• de grijze jas
• mijn grijze jas

But after is, it stays:

• De jas is grijs.

So the spelling change is grammatical, not a change of meaning.

Nothing unusual here. Dutch follows the usual pattern:

• Capital letter at the start: Mijn
• Period at the end: .
• Color words like grijs are not capitalized in normal use

So Mijn jas is grijs. is written exactly as you would expect for a normal statement.