De winkel is dinsdag open.

Because winkel is a de-word in Dutch. Nouns in Dutch take either de or het as their definite article, and winkel happens to use de.

So:

• de winkel = the shop/store
• not het winkel

Unfortunately, whether a noun takes de or het often just has to be learned along with the word.

In Dutch, days of the week often do not need a preposition when you mean on Tuesday, on Monday, and so on.

So:

• De winkel is dinsdag open. = The shop is open on Tuesday.

Dutch commonly says this without op. You can also hear op dinsdag, but in a simple sentence like this, leaving the preposition out is very normal and natural.

In Dutch, days of the week are normally written with a lowercase letter, unlike in English.

So:

• maandag
• dinsdag
• woensdag

This is the standard spelling unless the word happens to start a sentence.

Yes. Open is an adjective here, meaning open.

In De winkel is dinsdag open, the structure is:

• De winkel = subject
• is = verb
• dinsdag = time expression
• open = adjective/predicate adjective

So literally, the sentence is something like:

• The shop is Tuesday open

But in natural English, that becomes:

• The shop is open on Tuesday

Dutch word order often places time expressions before the final adjective or complement in a sentence like this.

So:

• De winkel is dinsdag open. is natural.
• De winkel is open dinsdag. sounds wrong or very unnatural.

A useful pattern is:

• subject + form of zijn + time expression + adjective

For example:

• De winkel is maandag dicht. = The shop is closed on Monday.
• Het museum is morgen open. = The museum is open tomorrow.

Yes, absolutely.

• De winkel is dinsdag open.
• De winkel is op dinsdag open.

Both are correct. The version without op is very common and efficient. The version with op can sound a bit more explicit.

Very roughly:

• dinsdag = on Tuesday
• op dinsdag = also on Tuesday, sometimes with a slightly more marked or formal feel depending on context

By itself, dinsdag can depend on context.

In a sentence like:

• De winkel is dinsdag open

it often means:

• The shop is open on Tuesday

That could refer to:

1. a specific Tuesday, if the context makes that clear
2. Tuesday as part of a schedule

If you want to make it clearly habitual, Dutch often says:

• De winkel is op dinsdag open. = The shop is open on Tuesdays / on Tuesday
• De winkel is elke dinsdag open. = The shop is open every Tuesday

So the exact meaning depends on context.

You usually use niet:

• De winkel is dinsdag niet open. = The shop is not open on Tuesday.

You may also hear:

• De winkel is dinsdag gesloten. = The shop is closed on Tuesday.

That second version is often more natural if you specifically want the idea of being closed.

Yes. If you put a time expression first in Dutch, the verb usually comes immediately after it because of the verb-second rule.

So you can say:

• Dinsdag is de winkel open.

That means the same thing, but it gives a little more emphasis to Tuesday.

Compare:

• De winkel is dinsdag open.
• Dinsdag is de winkel open.

Both are correct.

A practical pronunciation for English speakers is something like:

• DINZ-dakh or DINZ-dahkh

A few points:

• The first syllable is stressed: DIN
• The ie sounds like the vowel in see
• The final g in standard Dutch is a throaty sound that English does not really have

You do not need perfect pronunciation right away; saying something close to DINZ-dag will usually still be understood.

Yes, it can mean both shop and store in English.

So:

• De winkel is dinsdag open. could be translated as
  • The shop is open on Tuesday.
  • The store is open on Tuesday.

Which English word sounds best depends on the variety of English and the context.

The sentence follows a very common Dutch pattern:

• De winkel = subject
• is = verb
• dinsdag = time expression
• open = predicate adjective

So the pattern is:

• subject + zijn + time expression + adjective

You can reuse this pattern in many sentences:

• Het restaurant is vanavond druk. = The restaurant is busy tonight.
• De school is morgen dicht. = The school is closed tomorrow.
• Mijn broer is vandaag ziek. = My brother is sick today.