Μην ξεχάσεις το φλας πριν στρίψεις δεξιά.

It is a negative command: someone is telling one person not to forget something.

More specifically, it is:

• informal
• addressed to you (singular)
• about a single action in the future

So the tone is like: Don’t forget the indicator before you turn right.

Because δεν and μην do different jobs:

• δεν negates statements
• μην negates subjunctive forms, including negative commands

So:

• Δεν ξεχνάς το φλας = You are not forgetting the indicator / You don’t forget the indicator
• Μην ξεχάσεις το φλας = Don’t forget the indicator

In English, both might use not/don’t, but Greek makes a clear distinction.

In Modern Greek, negative commands are usually not made with an imperative form. Instead, Greek uses:

• μην + subjunctive

So:

• Μην ξεχάσεις = Don’t forget

This is the normal way to say it.

For comparison:

• positive command: Ξέχασε would mean Forget!
• negative command: Μην ξεχάσεις = Don’t forget!

ξεχάσεις is the aorist subjunctive, and here it refers to one complete action: forgetting something on this occasion.

That fits the meaning well:

• Μην ξεχάσεις = Don’t forget this one time

If you used μην ξεχνάς, that would sound more like:

• don’t keep forgetting
• don’t be forgetting
• don’t forget as a habit

So the sentence uses ξεχάσεις because it is about one specific driving situation.

Greek often leaves out subject pronouns when they are clear from the verb ending.

Here, the ending -εις shows that the verb is second person singular:

• ξεχάσεις = you forget
• στρίψεις = you turn

So Greek does not need to say εσύ here.

If you added εσύ, it would sound more emphatic:

• Μην ξεχάσεις εσύ το φλας...
  But in normal speech, that is usually unnecessary.

το φλας means the turn signal / indicator / blinker.

A few useful notes:

• φλας is a loanword
• it is treated as neuter
• it is commonly used in everyday Greek driving language

So:

• βάζω φλας = I use/put on the indicator
• ξέχασες το φλας = you forgot the indicator

Greek uses the definite article more often than English.

Here, το φλας refers to the specific thing you should use in that situation, so the article sounds natural.

English might sometimes say:

• Don’t forget your signal
• Don’t forget to use the indicator

Greek often expresses that with the noun plus article:

• το φλας

So even if English might not always use the, Greek often will.

After πριν (before), Greek very often uses the verb directly in the subjunctive-type form, without να:

• πριν φύγεις = before you leave
• πριν δεις = before you see
• πριν στρίψεις = before you turn

So πριν στρίψεις is completely normal.

You may also hear πριν να... in some contexts, but πριν στρίψεις is very common and standard.

For the same reason as ξεχάσεις: the sentence is talking about one single action.

• στρίψεις = you turn on one occasion, as a complete event
• στρίβεις = you are turning / you turn habitually

Here the meaning is:

• before you make that right turn

So στρίψεις is the natural choice.

Here δεξιά is an adverb, meaning:

• right
• to the right

So:

• στρίψεις δεξιά = turn right

It is not describing a noun here. It is describing how / in what direction you turn.

Compare:

• δεξιά στροφή = right turn
  Here δεξιά functions more like an adjective.
• στρίβω δεξιά = I turn right
  Here it is adverbial.

Yes. Greek word order is fairly flexible.

The given version is natural:

• Μην ξεχάσεις το φλας πριν στρίψεις δεξιά.

But you could also say:

• Πριν στρίψεις δεξιά, μην ξεχάσεις το φλας.

That means the same thing, but it puts a little more focus on the timing: before you turn right.

So the word order can change, but the original sentence is a very normal way to say it.

You would use the plural/formal verb forms:

• Μην ξεχάσετε το φλας πριν στρίψετε δεξιά.

So:

• ξεχάσεις / στρίψεις = informal singular
• ξεχάσετε / στρίψετε = plural or polite singular

This is the same distinction Greek uses in many commands.

A rough pronunciation is:

Min kseh-A-sis to flas prin STREE-psis dheks-YA.

A few pronunciation notes:

• χ in ξεχάσεις is like the ch in German Bach, not like English ch
• στρίψεις has the stress on the first syllable: STRI-
• δ in δεξιά is like th in this, not like English d
• ξ sounds like ks

So δεξιά is roughly dheks-YA.