Op mijn boodschappenlijst staan brood plus kaas voor het ontbijt.

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

That means:

• one element comes first,
• then the finite verb comes second.

Here, the prepositional phrase Op mijn boodschappenlijst is placed first for emphasis or topic, so the verb staan has to come next:

• Op mijn boodschappenlijst staan ...

After that comes the subject:

• brood plus kaas voor het ontbijt

A more neutral subject-first version is also possible:

• Brood plus kaas voor het ontbijt staan op mijn boodschappenlijst.

Both are grammatical.

There are two useful things to notice here.

1. Staan is often used in Dutch for things that are written, listed, or displayed somewhere.

So Dutch says things like:

• Op het bord staat een woord.
• Op de lijst staan drie namen.

2. The subject here refers to two items: brood and kaas. Because of that, the plural form staan is natural.

Compare:

• Op mijn boodschappenlijst staat brood. = one item
• Op mijn boodschappenlijst staan brood en kaas. = two items

So staan fits both the idea of being on a list and the fact that the subject is effectively plural.

Boodschappenlijst means shopping list or grocery list.

It is made from:

• boodschappen = groceries / shopping
• lijst = list

So literally it is something like groceries-list.

Because Dutch usually writes compound nouns as one word.

This is very common in Dutch:

• boodschappenlijst = shopping list
• huisdeur = house door / front door
• tafelkleed = tablecloth

Where English often uses two words, Dutch often joins them into one compound noun.

Because op is the normal preposition used with lists in Dutch.

Just like English often says on my list, Dutch says:

• op mijn lijst
• op de menukaart
• op het bord

The idea is that the words or items appear on the list or surface.

Because brood and kaas are being used here as general food items, not as specific, individually identified objects.

On shopping lists, Dutch often uses bare nouns like this:

• brood
• kaas
• melk
• boter

That is very natural.

If you wanted to be more specific, you could add an article or quantity word:

• een brood = a loaf of bread
• een stuk kaas = a piece of cheese
• twee broden = two loaves

But on a shopping list, just brood and kaas is completely normal.

Plus is understandable and natural, but en is more neutral and more common.

So these are both possible:

• brood plus kaas
• brood en kaas

Plus can sound a little more casual, list-like, or slightly emphatic, almost like bread, plus cheese.

If you want the safest, most standard choice, use en.

Because ontbijt is a het-word in Dutch.

So:

• het ontbijt = the breakfast

This is something you simply have to learn with the noun.

Also, in Dutch, meal words often appear with the article in phrases like:

• bij het ontbijt = at breakfast
• na het ontbijt = after breakfast
• voor het ontbijt = for breakfast / for the breakfast meal

Mijn means my. It is a possessive determiner.

So:

• mijn boodschappenlijst = my shopping list

In modern Dutch, mijn usually stays the same regardless of the noun:

• mijn boek
• mijn kaas
• mijn lijst

So unlike some other languages, you do not usually have to change it for gender or number.

Yes. That is a perfectly good Dutch sentence.

The difference is mainly in focus:

• Op mijn boodschappenlijst staan brood plus kaas voor het ontbijt.
  This starts with where the items are.

• Brood plus kaas voor het ontbijt staan op mijn boodschappenlijst.
  This starts with what the items are.

Both are grammatical. Dutch gives you some flexibility because of the verb-second pattern.

No. It is correct, but there are other possibilities depending on nuance.

For example:

• voor het ontbijt = for breakfast / intended for breakfast
• als ontbijt = as breakfast
• voor bij het ontbijt = to have with breakfast

Very roughly:

• als ontbijt focuses on what the breakfast itself will be
• voor bij het ontbijt suggests something to eat along with breakfast
• voor het ontbijt works well as a general purpose phrase in this sentence

So the given sentence is fine, but Dutch offers a few natural alternatives.