Podłoże jest suche.

Because podłoże is a neuter singular noun.

In Polish, adjectives must agree with the noun in:

• gender
• number
• case

The basic singular adjective endings are often:

• masculine: suchy
• feminine: sucha
• neuter: suche

So:

• suchy grunt = dry ground
• sucha ziemia = dry soil/earth
• suche podłoże = dry surface/substrate/ground

Since podłoże is neuter, suche is the correct form.

A very common clue is the ending -e.

Many Polish neuter nouns in the singular end in:

• -o
• -e
• -ę

So podłoże is treated as neuter, and that affects the adjective form and other grammar around it.

That said, endings are a strong clue, not a perfect rule for every noun in Polish. But for podłoże, neuter is correct.

In Polish, the verb być (to be) is normally used in the present tense in ordinary descriptive sentences like this one:

• Podłoże jest suche.

So unlike Russian, for example, Polish usually does not drop is/are in this kind of sentence.

You may sometimes hear shortened or more elliptical styles in headlines, notes, or very informal speech, but the standard full sentence is:

• Podłoże jest suche.

Podłoże is a fairly broad word. Depending on context, it can mean things like:

• the ground
• the surface
• the substrate
• the base layer
• the material something is resting or growing in

It is often used in:

• construction
• gardening
• sports surfaces
• technical descriptions
• geology or biology

So it is a bit more technical or neutral than a simple everyday word like ziemia (earth/soil) or grunt (ground/soil).

Yes, but it sounds a bit neutral or technical, depending on context.

You might hear it naturally in contexts like:

• construction: checking if a surface is dry enough
• sports: describing field conditions
• gardening: talking about planting medium or soil conditions
• manuals/instructions: checking whether the substrate has dried

In everyday casual conversation, a person might also choose a more specific noun, such as:

• ziemia jest sucha
• grunt jest suchy
• podłoga jest sucha

depending on what exactly is dry.

Yes, Polish word order is more flexible than English word order.

The neutral, straightforward order is:

• Podłoże jest suche.

But you could also hear:

• Suche jest podłoże.
• Jest suche podłoże.

These alternatives are less neutral and usually sound marked, emphatic, or context-dependent.

For a learner, the safest and most natural version is:

• Podłoże jest suche.

It is in the nominative singular.

This is because podłoże is the subject of the sentence, and in a basic sentence of the type X is Y, the subject is normally in the nominative.

Also, the adjective suche matches it in:

• nominative
• singular
• neuter

So the sentence is grammatically very regular:

• subject in nominative: podłoże
• verb: jest
• adjective agreeing with the subject: suche

A rough pronunciation guide is:

• pod-wo-zhe

More carefully:

• po sounds roughly like po in Poland
• dł is pronounced more like dw than a clear English dl
• ż sounds like the s in measure
• the stress is on the second-to-last syllable: pod-ŁO-że

So the stress falls on ło.

A rough English approximation is:

• pod-WO-zhe

In modern Polish, ł is usually pronounced like an English w sound.

So in podłoże, the part dł does not sound like English dl. Instead, it comes out approximately like dw.

This is why learners are often surprised that podłoże sounds closer to podwoże than to something with a clear l.

In this sentence, yes, it most naturally means physically dry.

The adjective suchy can also appear in other meanings depending on context, such as:

• dry weather
• dry skin
• dry humor/style
• dry facts or dry language

But with podłoże, the physical meaning is the obvious one: the surface or substrate lacks moisture.

Usually not if you just want the simple meaning of the sentence.

• jest = is
• bywa = is sometimes / tends to be at times

So:

• Podłoże jest suche. = states a present condition
• Podłoże bywa suche. = means the substrate is sometimes dry

That changes the meaning. For the basic sentence, jest is the right choice.

You would change the verb być and keep the adjective agreeing with podłoże.

Examples:

• Podłoże było suche. = past
• Podłoże będzie suche. = future

Because podłoże stays neuter singular, the adjective remains suche.

Very often in sentences of the type X is Y, yes:

• Podłoże jest suche.
• Dom jest duży.
• Kawa jest gorąca.

But Polish adjectives can also come before the noun when they directly describe it inside a noun phrase:

• suche podłoże = dry substrate/surface

So compare:

• Podłoże jest suche. = The substrate is dry.
• suche podłoże = dry substrate

Both are normal; they just have different sentence structures.