Radim noću.

Radim is the 1st person singular present tense form of raditi (to work).

So:

• ja radim = I work / I am working

In Serbian, the verb ending already shows the subject, so radim by itself naturally means I work.

A few related present-tense forms of raditi:

• radim = I work
• radiš = you work
• radi = he/she/it works
• radimo = we work
• radite = you work (plural/formal)
• rade = they work

Because Serbian often drops subject pronouns when they are clear from the verb form.

So:

• Radim noću. = I work at night.
• Ja radim noću. also means the same thing, but ja is usually added only for emphasis, contrast, or clarity.

For example:

• Ja radim noću, a on radi danju.
  I work at night, but he works during the day.

So in normal speech, Radim noću. is completely natural.

Noću is an adverbial form meaning at night or during the night.

In this sentence, it tells you when the action happens:

• Radim noću. = I work at night.

For learners, the easiest and most useful way to remember it is simply:

• noć = night
• noću = at night / by night / during the night

It is a very common expression, and you should treat noću as a fixed, natural way to say at night.

Because Serbian does not normally express at night that way in this context.

The natural everyday form is:

• noću

So:

• Radim noću. = natural
• Radim u noći. = generally not the normal way to say this
• Radim noć. = incorrect for this meaning

Serbian often uses special adverbial expressions for time, and noću is one of them.

Compare:

• danju = during the day / by day
• noću = during the night / at night

It can mean both, depending on context.

Serbian present tense often covers both:

• a habitual meaning: I work
• an ongoing meaning: I am working

So Radim noću. most naturally means:

• I work at night
  or
• I’m working nights

Because of noću, the sentence usually sounds habitual or regular, not like something happening only this very moment.

Because raditi is the normal imperfective verb for to work.

In Serbian, aspect matters:

• raditi = to work, to be working, to do work in a general or ongoing sense
• uraditi usually means to do/complete something, more like finish doing

So:

• Radim noću. = I work at night.
• Uradim noću would not mean the same thing and would sound wrong for talking about employment or a work schedule.

When talking about a job, routine, or ongoing activity, raditi is the correct verb.

Yes. Serbian word order is fairly flexible, although some orders are more neutral than others.

The most neutral version is:

• Radim noću.

You can also say:

• Noću radim.

That version puts more focus on noću—as if you were emphasizing at night.

For example:

• Danju spavam, noću radim.
  I sleep during the day; at night I work.

So both are possible, but Radim noću. is the plain, neutral sentence.

A helpful approximation is:

• noću ≈ NO-chyu

The important part for English speakers is ć.

Ć is a soft consonant, somewhat like a very soft ch sound. It is not exactly the same as English ch in church, but that is a useful approximation at first.

So:

• noć sounds roughly like nochy
• noću sounds roughly like NO-chyu

If you are just starting, producing a soft ch sound is usually good enough.

Usually, yes, but not necessarily only a formal job.

Radim can mean:

• I work in the sense of employment
• I’m working in the sense of doing work, being busy, or performing some task

So Radim noću. could mean:

• I have a night job / I work nights
• I do my work at night
• I’m active working during the night

The exact meaning depends on context, but the grammar of the sentence stays the same.

Yes—these are very useful and often learned together:

• danju = during the day / by day
• noću = during the night / at night
• ujutru = in the morning
• uveče = in the evening
• popodne = in the afternoon

Examples:

• Spavam danju. = I sleep during the day.
• Radim noću. = I work at night.
• Učim ujutru. = I study in the morning.
• Čitam uveče. = I read in the evening.

These expressions are very common in everyday Serbian.