Bez mapy vždycky zapomenu, kde mám zabočit vpravo.

Because bez always takes the genitive case in Czech.

• mapa = nominative singular, the basic dictionary form
• mapy = genitive singular

So:

• bez mapy = without a map

This is a very common pattern:

• bez auta = without a car
• bez peněz = without money
• bez problémů = without problems

Czech has no articles, so it does not have separate words for a, an, or the.

That means mapy can mean:

• a map
• the map

The exact meaning comes from context. In this sentence, English naturally says without a map, but Czech simply says bez mapy.

Vždycky means always.

Yes, you can also say vždy. The difference is mostly style:

• vždycky = very common in everyday speech
• vždy = also correct, but can sound a bit more formal or literary in some contexts

So both are possible:

• Bez mapy vždycky zapomenu...
• Bez mapy vždy zapomenu...

The version with vždycky sounds very natural in normal conversation.

This is about aspect, which is very important in Czech.

• zapomenout → perfective
• zapomínat → imperfective

So:

• zapomenu = I will forget / I end up forgetting
• zapomínám = I forget, I am forgetting, I tend to forget

In this sentence, vždycky zapomenu is very natural and means something like:

• every time, I end up forgetting

It presents the forgetting as a whole completed event each time.

If you said vždycky zapomínám, it would sound more like a general habit or tendency:

• I am always forgetting

Both can work, but vždycky zapomenu is very idiomatic here.

Literally, it means:

• where I have to turn
• where I am supposed to turn

In Czech, mám + infinitive is often used to express:

• what someone should do
• what someone is supposed to do
• what someone needs to do

So kde mám zabočit is a very natural way to say:

• where I should turn
• where to turn

Similar examples:

• Nevím, co mám dělat. = I do not know what I should do.
• Zapomněl jsem, kam mám jít. = I forgot where I should go.

This is a very good question.

Normally:

• kde = where, at what place
• kam = where to, to what destination

Here, kde mám zabočit asks about the place where the turn happens, not the destination after the turn.

So the idea is:

• At which point do I turn right?

That is why kde is natural.

If you used kam, it would shift the focus more toward where to go rather than where the turning point is.

Because the sentence already has vpravo, which gives the direction, kde works especially well.

Because zabočit is the perfective verb, and that fits a single turn in a route.

• zabočit = to turn, as one completed action
• zabočovat = to be turning / to turn repeatedly or in an ongoing sense

When giving directions or talking about one specific turn, Czech normally prefers the perfective verb:

• mám zabočit vlevo
• máš zabočit na druhé křižovatce

Using zabočovat here would sound less natural.

Yes, you could. Both are possible.

• vpravo = right, on the right, to the right
• doprava = to the right, rightward

With a verb like zabočit, both are common:

• zabočit vpravo
• zabočit doprava

Very roughly:

• doprava can sound a bit more clearly directional
• vpravo can sound slightly more like the position or side

But in practice, in route instructions, both are normal.

Because Czech uses a comma to separate a subordinate clause from the main clause.

Main clause:

• Bez mapy vždycky zapomenu

Subordinate clause:

• kde mám zabočit vpravo

So the comma is required.

This is very standard in Czech grammar.

No, Czech word order is fairly flexible, but different orders change the emphasis.

The given sentence:

• Bez mapy vždycky zapomenu, kde mám zabočit vpravo.

This sounds natural and emphasizes without a map early.

Other orders are possible, for example:

• Vždycky bez mapy zapomenu, kde mám zabočit vpravo.
• Bez mapy zapomenu, kde mám vždycky zabočit vpravo.

But the emphasis shifts, and some versions sound less natural in ordinary speech.

The original sentence is a good, idiomatic choice.

Grammatically yes, but the meaning changes.

• kde mám zabočit = where I should turn / where I am supposed to turn
• kde musím zabočit = where I must turn / where I have to turn

Musím sounds stronger and more forceful. It suggests necessity.

In this sentence, mám zabočit is more natural, because it is about remembering the correct route or instruction, not strong obligation.