Я иду в поликлинику вечером.

Russian has several verbs for “to go (on foot)”, and they are not interchangeable:

• идти → иду = to go / to be going (on foot) right now or one specific time
• ходить → хожу = to go (on foot) regularly, habitually, back and forth
• пойти → пойду = to set off / to start going (on foot), one-time, future-looking

So:

• Я иду в поликлинику вечером.
  Focus: this specific occasion (“I’m going / I’m on my way this evening”).

• Я хожу в поликлинику вечером.
  Focus: habit (“I (usually/regularly) go to the clinic in the evenings”).

• Я пойду в поликлинику вечером.
  Focus: decision / plan to start going at that time (“I will go / I’ll set off to the clinic in the evening”).

The original sentence talks about one specific trip (tonight or some evening already decided), so иду is natural.

Literally, идти / иду means to go on foot, to walk.

In careful, precise Russian:

• иду = going on foot
• еду = going by transport (car, bus, train, etc.)

So:

• Я иду в поликлинику вечером. – I’m walking to the clinic in the evening.
• Я еду в поликлинику вечером. – I’m going to the clinic (by bus/car/etc.) in the evening.

In casual speech, some people may stretch идти a bit more generally, but if you want to be correct and clear, use:

• идти – on foot
• ехать – by vehicle

After the preposition в meaning “to, into” (direction), Russian uses the accusative case.

• Nominative (dictionary form): поликлиника
• Accusative (with motion “into”): поликлинику

So the pattern is:

• Я иду в поликлинику. – I’m going to the clinic.
• Я в поликлинике. – I am in the clinic (prepositional case, location).

Rule to remember:

• в + Accusative → motion into / to a place
• в + Prepositional → in / at a place

Both в and к can sometimes translate as “to”, but they are different:

• в + accusative (в поликлинику) = into, inside the place
  → Focus: entering / going inside the building.

• к + dative (к поликлинике) = towards, to (up to) something
  → Focus: approaching it, not necessarily going inside.

So:

• Я иду в поликлинику. – I’m going to the clinic (to go inside).
• Я иду к поликлинике. – I’m going towards the clinic (to that area / up to it).

In your sentence, you mean going to the clinic as a place where you’ll enter, so в поликлинику is correct.

Вечером is the instrumental case of вечер (“evening”), and in Russian, time expressions in the instrumental often work as adverbs of time, without a preposition.

Common patterns:

• утро → утром – in the morning
• день → днём – in the daytime / in the afternoon
• вечер → вечером – in the evening
• ночь → ночью – at night

So you just say:

• Я иду в поликлинику вечером. – I’m going to the clinic in the evening.

You do not say в вечером. The case ending -ом / -ью itself expresses the “in/at that time” meaning.

Yes, you can say:

• Вечером я иду в поликлинику.

Both:

• Я иду в поликлинику вечером.
• Вечером я иду в поликлинику.

are grammatically correct and mean the same basic thing.

Nuance of word order:

• Я иду в поликлинику вечером.
  More neutral; the sentence starts with the subject я. The time вечером is extra information at the end.

• Вечером я иду в поликлинику.
  Slightly more emphasis on when: “As for the evening, (that’s when) I’m going to the clinic.”

In everyday speech, both are very natural; the difference is subtle and mostly about rhythm and focus.

To express habit / regular action, use ходить instead of идти:

• Я обычно хожу в поликлинику вечером.

Breakdown:

• я – I
• обычно – usually
• хожу – I (regularly) go (on foot)
• в поликлинику – to the clinic
• вечером – in the evening

Compare:

• Я иду в поликлинику вечером. – I’m going (this time, this evening).
• Я обычно хожу в поликлинику вечером. – I usually go to the clinic in the evening (habit).

Grammatically, иду is present tense of идти.

However, in Russian the present tense of a motion verb can describe a near future arrangement, especially with a time expression:

• Я иду в поликлинику вечером.
  Literally: I am going to the clinic in the evening, but it also naturally means I’m going (will go) this evening.

Context + the word вечером make it clear it’s about the future. This is similar to English “I am going to the doctor tomorrow”: grammatically present, but future in meaning.

Russian does not have a / an / the, so в поликлинику can correspond to either “to the clinic” or “to a clinic”, depending on context.

• If both speaker and listener know which clinic is meant (e.g. their local one), you’d translate it as “to the clinic”.
• If it’s not a specific known clinic, you might translate it as “to a clinic”.

The Russian phrase itself is neutral; specific vs non-specific meaning comes from the context, not from an article.

Approximate pronunciation (stressed syllables in bold):

• иду – [ee-DOO]

  • Stress: on -ду
  • The initial я in full form я иду is [ya ee-DOO].

• поликлинику – [pə-lee-KLEE-nee-koo]

  • Stress: on кли: по-ли-кли-ни-ку

• вечером – [VYE-chee-rəm]

  • Stress: on ве: ве-че-ром
  • е after в is pronounced like “vye”.

Russian stress is fixed per word but not predictable by rule, so you generally need to learn it word by word.

You can drop the pronoun and say:

• Иду в поликлинику вечером.

Russian is a pro-drop language: the verb ending (-у in иду) already shows the subject is “I”, so я is often omitted if the subject is clear from context.

• Я иду в поликлинику вечером. – neutral, full form.
• Иду в поликлинику вечером. – also natural, a bit more informal / conversational, or used when the subject is obvious.

Using я can add a little extra emphasis on I (“I’m the one going…”), but often it’s just stylistic.

Поликлиника is a feminine noun ending in -а.

Its singular declension (some key cases):

• Nominative (subject): поликлиника – The clinic is new.
• Accusative (motion into/towards, or direct object): поликлинику – I’m going to the clinic.
• Prepositional (location): в поликлинике – I am in the clinic.

Feminine nouns ending in -а usually change -а → -у in the accusative case (when they are the direct object or after motion в / на with direction):

• в школу (from школа)
• в комнанту (from комната)
• в поликлинику (from поликлиника)

So here в поликлинику uses the accusative to show direction: “into/to the clinic.”

Yes. The structure with идти / ходить + в + accusative + [time in instrumental] is very common.

Examples:

• Я иду в поликлинику утром. – I’m going to the clinic in the morning.
• Я иду в поликлинику днём. – I’m going to the clinic in the daytime / in the afternoon.
• Я иду в поликлинику ночью. – I’m going to the clinic at night.

Time words:

• утро → утром – in the morning
• день → днём – in the daytime
• вечер → вечером – in the evening
• ночь → ночью – at night

All of them work like вечером in your original sentence.