Ajde, idemo kući.

Ajde is a very common conversational word meaning something like come on, okay then, or let’s depending on context.

In Ajde, idemo kući, it works like an encouraging push:
Come on, let’s go home.

It is not the main verb of the sentence. The main action is in idemo.

You will hear ajde a lot in everyday speech:

• Ajde! = Come on!
• Ajde, sedi. = Come on, sit down.
• Ajde, pričaj. = Go on, talk.

In Serbian, the 1st person plural present tense often does the job of English let’s ...

So idemo literally looks like we go / we are going, but in context it can mean:

• we’re going
• let’s go

That is very normal in Serbian.

So:

• Idemo! = Let’s go!
• Idemo kući. can mean either We’re going home or Let’s go home, depending on context.
• Adding ajde strongly pushes it toward the let’s go home meaning.

Because Serbian usually does not need subject pronouns when the verb already shows the person and number.

Idemo already tells you it is we:

• -mo = we

So mi idemo kući is possible, but mi is usually unnecessary unless you want emphasis or contrast.

For example:

• Mi idemo kući, a oni ostaju. = We’re going home, and they are staying.

In your sentence, just idemo is the natural choice.

Kući is the form used when you mean home as a destination.

The basic noun is kuća = house.
But after verbs of motion, Serbian very often uses kući to mean to home / homeward:

• Idem kući. = I’m going home.
• Vraćamo se kući. = We’re returning home.

For a learner, the easiest way to remember it is:

• kuća = the house
• kući = home, when someone is going there

Grammatically, kući is historically a case form of kuća, but in everyday learning it is best treated as the normal fixed form after verbs like ići, doći, vratiti se, and similar.

This is a very important distinction.

• kući = home, as a destination

  • Idemo kući. = We’re going home.

• kod kuće = at home, location

  • Ja sam kod kuće. = I’m at home.

• u kuću = into the house

  • Ulazimo u kuću. = We’re going into the house.

So in your sentence, kući is correct because the idea is not just going into a building, but going home.

Yes. Ajde and hajde are both used, and they mean the same thing here.

Very often:

• hajde feels a bit fuller or more careful
• ajde feels more relaxed and colloquial

In everyday speech, many speakers drop the h, so ajde is extremely common.

So all of these are natural:

• Ajde, idemo kući.
• Hajde, idemo kući.

Yes, it is mostly informal everyday speech.

It sounds natural with:

• friends
• family
• children
• classmates
• coworkers in casual situations

Ajde especially gives it a conversational tone.

If you wanted something more neutral or less conversational, you might simply say:

• Idemo kući.

In very formal or literary language, you might choose different wording, but for normal spoken Serbian, your sentence is completely natural.

Yes. By itself, Idemo kući can mean either:

• We are going home or
• Let’s go home

Context tells you which one is meant.

Examples:

• If someone asks Gde ste krenuli? then Idemo kući probably means We’re going home.
• If people are deciding what to do next, Idemo kući can mean Let’s go home.

In your full sentence, Ajde, idemo kući, the presence of ajde makes the suggestion/invitation meaning much stronger.

A simple learner-friendly guide is:

• Ajde ≈ EYE-deh
• idemo ≈ EE-deh-mo
• kući ≈ KOO-chee, but with a softer ć sound than English ch

A few helpful notes:

• Serbian j sounds like English y
• ć is softer than č
• the final i in kući is clearly pronounced

So the whole sentence is roughly:

EYE-deh, EE-deh-mo KOO-chee

That is only an approximation, but it is a good starting point.

Yes, those are also possible, but they have slightly different flavor.

• Ajde, idemo kući. = very common, conversational
• Ajmo kući. = also very common in many varieties; more compact
• Hajdemo kući. = correct, but can sound a bit less casual depending on region and situation

So for everyday spoken Serbian, your original sentence is one of the most natural ways to say it.