Głównie używamy mapy turystycznej.

Because używać usually takes the genitive case in Polish.

So the base form is:

• mapa turystyczna = nominative, the dictionary form

But after używać, it changes to genitive:

• mapy turystycznej

This is a very common thing learners notice, because in English use takes a direct object without any visible case change, but in Polish the verb używać behaves differently.

Używamy is the 1st person plural present tense form of używać.

It means:

• we use
• we are using
• sometimes we usually use, depending on context

The ending -my tells you the subject is we.

So:

• używam = I use
• używasz = you use
• używamy = we use

Because in Polish, the verb ending already shows who the subject is.

In używamy, the ending -my already means we, so my is usually unnecessary.

You can add my if you want emphasis, for example:

• My głównie używamy mapy turystycznej. = We mainly use a tourist map.

But in a neutral sentence, Polish usually leaves the subject pronoun out.

Głównie is an adverb meaning mainly, mostly, or primarily.

It tells you that this is the principal thing being used, not necessarily the only thing.

In this sentence, it modifies the whole idea of using:

• Głównie używamy mapy turystycznej.
• literally: Mainly, we use a tourist map.

Yes, Polish word order is fairly flexible.

Putting głównie first gives it a little emphasis. But other placements are also possible, for example:

• Głównie używamy mapy turystycznej.
• Używamy głównie mapy turystycznej.

Both are natural. The difference is mainly about emphasis and rhythm, not basic meaning.

Polish often moves words around more freely than English, as long as the endings still show the grammatical relationships.

Because both words have to match the genitive singular feminine form.

The noun:

• mapa → mapy

The adjective describing it:

• turystyczna → turystycznej

This agreement is normal in Polish: adjectives change to match the noun in:

• gender
• number
• case

So if the noun changes case, the adjective changes too.

Not in standard Polish with the verb używać.

Mapę turystyczną is the accusative form, and używać normally requires the genitive, not the accusative.

So the correct form here is:

• używamy mapy turystycznej

This is one of those verb patterns that just has to be learned.

They are an aspect pair:

• używać = imperfective
• użyć = perfective

In this sentence, używamy is imperfective because it describes a general, ongoing, or habitual action: we mainly use...

If you used użyć, it would sound more like a completed single action, for example to use something once / to make use of it.

So here używamy is the natural choice.

Yes, very often you can.

A common alternative is:

• Głównie korzystamy z mapy turystycznej.

That also means We mainly use a tourist map.

The structure is different, though:

• używać
  • genitive
• korzystać z
  • z
    • genitive

Both are correct, but korzystać z can sound a bit more like make use of / rely on.

A few useful pronunciation points:

• gł: the ł sounds like English w
• ó sounds like u
• nie is roughly like nye

So głównie is approximately:

• GWOO-vnye

Not a perfect English spelling, but close enough to help.

Also:

• używamy: the ż sounds like the s in measure
• turystycznej has stress on the second-to-last syllable, like most Polish words

Grammatically, mapy turystycznej is singular genitive, so it refers to one tourist map.

If you wanted tourist maps in the plural, the form would be different, for example:

• Głównie używamy map turystycznych.

So the sentence you have is singular, not plural.