Rano idę do przychodni.

Because rano is an adverb, not a noun phrase.

In English, you say in the morning, but in Polish you often just use the adverb rano = in the morning / this morning / mornings, depending on context.

So:

• Rano idę do przychodni. = I’m going to the clinic in the morning.

You would not normally say w rano.

A similar word is rankiem, which also means in the morning, but rano is the most common everyday choice.

This is a very common Polish motion-verb distinction.

• iść / idę = going in one specific instance, one direction, one trip
• chodzić / chodzę = going habitually, repeatedly, or in general

So:

• Rano idę do przychodni.
  This suggests a specific trip to the clinic, for example this morning or on a particular occasion.

• Rano chodzę do przychodni.
  This would suggest a habit or repeated action, for example if someone regularly goes there in the mornings.

English often uses go for both ideas, but Polish splits them.

Grammatically, idę is present tense.

However, in Polish, present-tense motion verbs are very often used for a planned near future, just like English:

• Tomorrow I’m going to the clinic.
• Jutro idę do przychodni.

So in this sentence, idę can mean:

• I’m going
• I’m going later / this morning depending on context.

So it is present in form, but it can refer to a future planned movement.

Because Polish verb endings usually already show who the subject is.

• idę = I go / I’m going

So ja is not necessary.

Polish often leaves subject pronouns out unless you want to add emphasis, contrast, or clarity.

Compare:

• Rano idę do przychodni. = neutral
• Ja rano idę do przychodni. = I am going to the clinic in the morning (maybe contrasting with someone else)

This is similar to Spanish or Italian, but unlike English, where the pronoun is usually required.

After the preposition do, Polish normally uses the genitive case when talking about movement to a place.

The dictionary form is:

• przychodnia = clinic

After do, it changes to:

• do przychodni

So:

• przychodnia = nominative
• przychodni = genitive singular

This is why the ending changes.

Przychodnia usually means an outpatient clinic, medical clinic, health center, or doctor’s clinic.

It is not quite the same as:

• szpital = hospital
• lekarz = doctor

So:

• Idę do przychodni = I’m going to the clinic / medical center
• Idę do lekarza = I’m going to the doctor

In real life, these can overlap in meaning, but the focus is different:

• przychodnia = the place
• lekarz = the person

Because Polish uses different prepositions with different destinations, and these combinations are often idiomatic.

For przychodnia, the normal expression is:

• iść do przychodni

So you should learn it as a set phrase:

• do przychodni
• do szkoły
• do szpitala

But some other destinations use na:

• na pocztę = to the post office
• na uczelnię = to university
• na lotnisko = to the airport

Unfortunately, this is not always fully predictable, so it often has to be memorized.

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

The basic meaning stays the same, but the focus can change.

For example:

• Rano idę do przychodni. = emphasis on morning
• Idę rano do przychodni. = more neutral
• Do przychodni idę rano. = emphasis on the clinic

The version you were given sounds very natural and puts the time first.

Yes, but it means something slightly different.

• Idę do przychodni. = I’m going to the clinic
• Idę do lekarza. = I’m going to the doctor

The first focuses on the place. The second focuses on the person you are going to see.

Sometimes both could fit the same real-world situation, but they are not identical.

A learner-friendly approximation is:

• idę ≈ EE-deh, with the last vowel slightly nasal
• przychodni ≈ pshih-HOD-nyi

A few useful details:

• ę is a nasal vowel. At the end of a word, learners can say it almost like e at first; that is much better than overcomplicating it.
• ch sounds like the ch in German Bach or Scottish loch, not like English ch in chair.
• ni sounds soft, roughly like nyi.

So the whole sentence is roughly:

• RA-no EE-deh do pshih-HOD-nyi

That is only an approximation, but it is a good start.