A köd miatt visszafordulunk.

Miatt means because of, due to, or on account of.

In this sentence, a köd miatt means because of the fog.

It is used with a noun:

• az eső miatt = because of the rain
• a hó miatt = because of the snow
• a köd miatt = because of the fog

Because miatt is a postposition, not a preposition.

English uses prepositions before the noun:

• because of the fog

Hungarian often uses postpositions after the noun:

• a köd miatt

So the structure is literally closer to:

• the fog because-of

This is completely normal in Hungarian.

A is the definite article, meaning the.

So a köd literally means the fog.

Hungarian often uses the definite article in places where English may or may not use it, depending on style and context. In this sentence, a köd miatt is very natural, even if English might simply say because of fog or because of the fog.

It can be broken down like this:

• vissza = back
• fordul = turn
• -unk = we (verb ending)

So visszafordulunk literally means something like we turn back or we turn around and go back.

The whole verb acts as one unit here.

The ending -unk shows that the subject is we.

So:

• fordulok = I turn
• fordulsz = you turn
• fordul = he/she/it turns
• fordulunk = we turn

In visszafordulunk, the same -unk ending tells you we are doing the action.

Because Hungarian usually does not need a separate subject pronoun if the verb ending already shows who the subject is.

So:

• visszafordulunk already means we turn back

You could add mi = we, but usually only for emphasis:

• Mi visszafordulunk. = We are turning back.

Without emphasis, leaving it out is more natural.

Formally, it is present tense.

But Hungarian present tense can often express:

• a present action: we are turning back
• a near-future action: we will turn back

So the exact English translation depends on context. On its own, this sentence most naturally means:

• We’re turning back because of the fog or
• We turn back because of the fog

In the right situation, it could also mean:

• We’ll turn back because of the fog

Yes. Hungarian word order is fairly flexible, and changes in word order often affect emphasis rather than basic meaning.

Your sentence:

• A köd miatt visszafordulunk.

This is a natural sentence and makes the reason a starting point/topic.

You could also say:

• Visszafordulunk a köd miatt.

That is also grammatical and natural.

The meaning stays basically the same, but the information is presented a little differently.

Yes, it can move in some sentence types.

In visszafordulunk, vissza is a verb prefix (more precisely, a preverbal particle). In a neutral statement, it usually stands directly before the verb:

• visszafordulunk

But in some environments, it moves after the verb, especially:

• with negation
• with certain kinds of focus

For example:

• Nem fordulunk vissza. = We are not turning back.
• A köd miatt fordulunk vissza. = It is because of the fog that we are turning back.

So yes: the prefix is not always stuck in front.

Because miatt is a separate postposition, and the noun before it usually stays in its basic form.

So you get:

• a köd miatt
• az eső miatt
• a baleset miatt

This is different from a case ending, where the noun itself would change by taking a suffix.

Not in exactly the same way.

• miatt is used with a noun
• mert is used to introduce a clause

So:

• A köd miatt visszafordulunk. = We are turning back because of the fog.
• Visszafordulunk, mert nagy a köd. = We are turning back because the fog is thick / because it is very foggy.

So miatt and mert are related in meaning, but they are not interchangeable in structure.

A few useful points:

• köd: the ö is like German ö or French eu in some words, not like English o
• sz in Hungarian sounds like English s
• s by itself sounds like English sh

So in visszafordulunk:

• the sz sound is an s sound
• the word begins roughly vissza-
• the whole verb is pronounced something like VIS-saw-for-du-lunk, though that is only an approximation

Also, miatt has a long final consonant sound: the tt is pronounced longer than a single t.

It can mean both, depending on context.

Very often, visszafordul means:

• turn back
• go back
• head back
• turn around and return

So in this sentence, it most likely means that the speakers decide not to continue because of the fog, and instead go back. It does not have to describe only the physical turning movement itself; it can describe the whole action of reversing course.