Powoli schodzę po schodach.

Powoli means slowly. It is an adverb, so it describes how the action is done.

It appears at the beginning because Polish word order is fairly flexible. Putting powoli first gives a little emphasis to the manner of the action:

• Powoli schodzę po schodach. = I’m going down the stairs slowly.
• Schodzę powoli po schodach. = same basic meaning, just a different emphasis

Both are natural.

Schodzę is the 1st person singular present tense form of the verb schodzić, which means to go down, to come down, or to descend.

So:

• schodzić = infinitive
• schodzę = I go down / I am going down

The ending -ę tells you the subject is I.

Because schodzić specifically includes the idea of moving downward.

Compare:

• iść = to go, to be going
• chodzić = to go/walk habitually or repeatedly
• schodzić = to go down, descend

So if you want to say I am going down the stairs, schodzić is the natural choice, because the downward direction is important.

It can mean either, depending on context.

Because schodzić is an imperfective verb, its present tense can describe:

• an action happening right now
  
  • Powoli schodzę po schodach. = I’m going down the stairs slowly.
• a habitual/repeated action
  
  • for example, if someone always walks carefully downstairs

Without more context, many learners will understand it as I’m going down the stairs slowly.

Because Polish usually leaves out subject pronouns when they are already clear from the verb form.

In schodzę, the ending -ę already tells you the subject is I. So ja is not necessary.

You could say:

• Ja powoli schodzę po schodach.

But that would usually add emphasis, contrast, or emotion, such as:

• Ja schodzę po schodach, a nie wbiegam.
  I’m going down the stairs, not running up them.

Schodach is in the locative plural.

That is because the preposition po often takes the locative, and with movement expressions it can mean something like along, over, or using a surface/path.

So:

• po schodach = on/along the stairs, in the sense of moving via the stairs

This is a very common Polish pattern:

• iść po schodach = to go on/up/down the stairs
• biec po schodach = to run on the stairs
• schodzić po schodach = to go down the stairs

The normal Polish word is schody, and it is used as a plural noun, much like English stairs.

So you get forms like:

• schody = stairs
• schodów = of/from the stairs
• schodach = on the stairs

A learner often expects a singular form meaning a staircase, but in ordinary Polish, schody is the standard everyday word.

If you want to refer to a single step, that is a different word:

• stopień or schodek = step

Because na schodach usually means on the stairs as a location, not down the stairs as a path of movement.

Compare:

• Jestem na schodach. = I am on the stairs.
• Schodzę po schodach. = I am going down the stairs.

So na schodach is more static, while po schodach works naturally with movement along the stairs.

Yes, you can, and it is also natural Polish.

There is a nuance:

• schodzę po schodach focuses on the path: I’m going down along the stairs / using the stairs
• schodzę ze schodów focuses more on moving off/from the stairs

In everyday speech, both can refer to going down the stairs, but po schodach is especially useful when talking about movement on the stairs themselves.

Yes. Polish word order is flexible, and changing it usually changes emphasis, not the core meaning.

Possible versions:

• Powoli schodzę po schodach.
• Schodzę powoli po schodach.
• Po schodach schodzę powoli. — possible, but more marked or stylistic

The most neutral choices are usually the first two.

A rough pronunciation guide is:

poh-VOH-lee SKHOH-dzeh pɔ SKHOH-dakh

A few useful points:

• w sounds like English v
• sch sounds like a hard sh/ch cluster, roughly like s
  • the ch in Scottish loch or German Bach
• rz is not separate here; in schodzę, the dz is pronounced together
• final ę in schodzę is often pronounced less strongly than learners expect in normal speech

If you want a more technical version, the pronunciation is approximately:

[pɔˈvɔlʲi ˈsxɔd͡zɛ̃ pɔ ˈsxɔdax]

Yes: the verb changes shape a little when it is conjugated.

You start with the infinitive:

• schodzić

But the I form is:

• schodzę

So you do not simply remove -ić and add something mechanically. This kind of stem change is normal in Polish verbs, and it is something learners usually just memorize with the whole present-tense pattern.

For example:

• schodzę = I go down
• schodzisz = you go down
• schodzi = he/she/it goes down
• schodzimy = we go down
• schodzicie = you all go down
• schodzą = they go down

So schodzę is a normal conjugated form, even though it may not look immediately obvious from the infinitive.