Ten pokój jest ładniejszy niż tamten.

These are demonstrative adjectives, meaning words like this and that.

• ten pokój = this room
• tamten pokój = that room

They must agree with the noun in gender, number, and case. Since pokój is masculine singular nominative, both demonstratives appear in their masculine singular nominative forms:

• ten
• tamten

So Polish is being more explicit than English: both this and that are grammatically matched to pokój.

Pokój is a masculine noun in Polish.

That matters because adjectives and demonstratives have to agree with it:

• ten pokój
• ładniejszy pokój
• tamten pokój

If the noun were feminine, the forms would change. For example:

• ta lampa
• ładniejsza lampa
• tamta lampa

So the -y ending in ładniejszy is there because pokój is masculine.

In Polish, you usually do use jest when the verb means is in an ordinary descriptive sentence like this:

• Ten pokój jest ładniejszy niż tamten.

That is the normal way to say This room is prettier than that one.

Polish can sometimes omit forms of to be, but not in standard simple comparisons like this. Omitting jest here would sound incomplete or unnatural.

Ładniejszy is the comparative form of ładny (pretty / nice).

• ładny = pretty, nice
• ładniejszy = prettier, nicer

This is a common Polish pattern: many adjectives form the comparative with -szy or -iejszy / -niejszy, often with small stem changes.

So:

• ładny → ładniejszy

You do not need to memorize every comparative purely by rule, because stem changes can be a bit unpredictable. It is often best to learn comparatives together with the basic adjective.

Polish often prefers a single-word comparative when one exists.

So for ładny, the natural comparative is:

• ładniejszy

Instead of:

• bardziej ładny

Bardziej ładny is understandable, but it sounds less natural here. In everyday Polish, ładniejszy is the normal choice.

A rough guideline:

• If a simple comparative exists and is common, use it.
• Bardziej + adjective is more common when a simple comparative is awkward, uncommon, or stylistically less preferred.

Niż means than in comparisons.

So:

• ładniejszy niż tamten = prettier than that one

It connects the two things being compared.

Very literally, the structure is:

• This room is prettier than that one.

In Polish, niż is one of the main words used for this kind of comparison.

Yes, often you can.

You can say:

• Ten pokój jest ładniejszy niż tamten.
• Ten pokój jest ładniejszy od tamtego.

Both mean roughly the same thing.

But there is an important grammar difference:

• after niż, you often keep the compared item in the same visible form as a full phrase: niż tamten
• after od, you use the genitive: od tamtego

So:

• niż tamten
• od tamtego

For learners, niż is often easier at first because the form can look more straightforward in simple sentences.

Because this sentence uses niż, not od.

Compare:

• Ten pokój jest ładniejszy niż tamten.
• Ten pokój jest ładniejszy od tamtego.

After od, Polish requires the genitive, so tamten changes to tamtego.

After niż, you commonly see the nominative-style form in simple comparisons like this:

• niż tamten

So the difference is tied to the comparison word used.

You can say niż tamten pokój, but Polish often leaves out the repeated noun when it is obvious.

So both are possible:

• Ten pokój jest ładniejszy niż tamten.
• Ten pokój jest ładniejszy niż tamten pokój.

The shorter version is very natural because everyone already knows tamten refers to pokój.

English does the same thing:

• This room is prettier than that.
• This room is prettier than that room.

Yes. The comparative adjective must agree with the noun.

Examples:

• masculine: ten pokój jest ładniejszy
• feminine: ta lampa jest ładniejsza
• neuter: to okno jest ładniejsze

So the ending changes:

• -szy for masculine
• -sza for feminine
• -sze for neuter

That agreement is a very important feature of Polish grammar.

Yes, Polish word order is more flexible than English, although some versions sound more neutral than others.

The most neutral version is:

• Ten pokój jest ładniejszy niż tamten.

You might also hear variations for emphasis, such as:

• Ładniejszy jest ten pokój niż tamten.
• Ten pokój jest ładniejszy od tamtego.

But for learners, the original order is the best and safest pattern to use.

Not exactly. Ładny usually means something like:

• pretty
• nice-looking
• attractive

For a room, it can mean nice, pretty, or pleasant-looking.

It is often less strong than beautiful. So depending on context, ładniejszy might be best understood as:

• prettier
• nicer-looking
• sometimes nicer

So the sentence is comparing appearance or visual appeal.

A few helpful points:

• pokój: the ó sounds like u in modern Polish, and the stress is on the second-to-last syllable: po-KUY or more accurately PO-kuy with Polish sounds.
• ładniejszy: the ł sounds like English w; ni sounds roughly like a soft ny; stress is on the second-to-last syllable: wad-NYEY-shy approximately.
• niż: sounds roughly like neesh with a short Polish vowel.

A couple of extra pronunciation notes:

• ł = like English w
• ż = like the s in measure
• ń / ni before a vowel or consonant often has a soft ny quality

Exact pronunciation takes practice, but those approximations can help you get started.

No. Ten specifically means this, not the.

Polish has no articles like English the and a/an. So:

• pokój can mean a room or the room, depending on context
• ten pokój specifically means this room

That is why ten is not just a filler word. It adds real meaning: it points to a particular room near the speaker or already in focus.