Μην πατάς τα λουλούδια στην αυλή.

Because this is a negative command: Don’t step on the flowers...

In Greek:

• δεν negates ordinary statements: Δεν πατάς τα λουλούδια = You are not stepping on the flowers / You don’t step on the flowers
• μην is used for prohibitions and other non-indicative uses: Μην πατάς τα λουλούδια = Don’t step on the flowers

So μην is the correct negative word here.

Πατάς is the 2nd person singular form of πατάω / πατώ.

That means it is used when speaking to one person in an informal way:

• (εσύ) πατάς = you step / you are stepping

With μην, it becomes the normal way to make a negative command:

• Μην πατάς = Don’t step

So the sentence is addressed to one person: a child, a friend, someone nearby, etc.

Functionally, yes: it is a command.

But in Modern Greek, a negative imperative is usually not formed with a special imperative verb form. Instead, Greek normally uses:

• μην + verb form

So instead of a separate negative imperative like English don’t step, Greek says:

• Μην πατάς

That is the standard way to say a negative command.

Both are possible, but they give slightly different shades of meaning.

• Μην πατάς τα λουλούδια = Don’t step on the flowers
  This often sounds more like a general or ongoing prohibition.
• Μην πατήσεις τα λουλούδια = Don’t step on the flowers
  This often sounds more like be careful not to step on them even once

A simple way to think about it:

• πατάς = imperfective, more general / repeated / ongoing
• πατήσεις = perfective, more single-event focused

In real life, both can be heard, but Μην πατάς τα λουλούδια is very natural.

Because Greek often uses πατάω directly with an object.

So Greek can say:

• πατάω τα λουλούδια
  literally something like step the flowers

but in natural English we translate that as:

• step on the flowers

This is just a difference in how the two languages build the expression. Greek does not need a separate word equivalent to English on in this sentence.

Τα λουλούδια is the plural form of το λουλούδι.

• το λουλούδι = the flower
• τα λουλούδια = the flowers

It is also in the accusative case, because it is the object of the verb πατάς.

So:

• πατάς τι; = what are you stepping on?
• τα λουλούδια = the flowers

For neuter nouns like this, the nominative and accusative plural are the same form, so you just see τα λουλούδια.

Στην is a contraction of:

• σε + την → στην

So:

• σε = in / at / to / on depending on context
• την = the (feminine accusative singular)

And αυλή means yard / courtyard

So:

• στην αυλή = in the yard / in the courtyard

English uses different prepositions depending on context, but Greek σε covers a lot of that ground.

Because αυλή is a feminine noun, and after σε it appears in the accusative singular.

For this noun:

• nominative: η αυλή
• accusative: την αυλή

The noun itself looks the same here; the article shows the case clearly:

• η αυλή = the yard as subject
• στην αυλή = in the yard

So the important change is mainly in the article: η becomes την inside στην.

Not completely. Greek word order is more flexible than English.

This sentence:

• Μην πατάς τα λουλούδια στην αυλή

is a very natural, neutral order:

1. negative command
2. verb
3. object
4. place

Greek could rearrange parts for emphasis, but this version sounds straightforward and normal.

Also, μην usually comes right before the verb phrase, so starting with Μην πατάς... is exactly what you would expect.

You would use πατάτε instead of πατάς:

• Μην πατάτε τα λουλούδια στην αυλή.

This can mean:

• Don’t step on the flowers in the yard when speaking to several people
• or the same thing said politely to one person

So:

• πατάς = singular informal
• πατάτε = plural or polite singular

A rough English-style guide:

• λουλούδια ≈ loo-LOO-thya
• αυλή ≈ av-LEE

A few details:

• In αυλή, αυ is pronounced av here because the next sound is voiced.
• The stress is important:
  • λουλούδια
  • αυλή

So the whole sentence is roughly:

• meen pa-TAS ta loo-LOO-thya stin av-LEE

No. Πατάω / πατώ has several related meanings, including:

• step on
• tread on
• press

For example:

• Πατάω το κουμπί = I press the button
• Πρόσεχε πού πατάς = Watch where you step
• Μην πατάς τα λουλούδια = Don’t step on the flowers

So its exact meaning depends on the object and context. Here, with flowers, it clearly means step on / trample.