Можно присоединиться к нам.

Можно means it is possible / it is allowed / one may. In this sentence, it works like May I...?/Is it okay to...? depending on context.

Russian often leaves the person unstated, so Можно присоединиться к нам literally feels like Is it possible to join us? but in real use it often means May I join you?

Russian often omits the subject when it is understood from context.

So Можно присоединиться к нам does not literally contain I, but the speaker is usually talking about themselves:

• Можно присоединиться к вам? = May I join you?
• Можно присоединиться к нам? can also be used in context where the meaning is understood as Can someone join us? or Is it possible to join us?

The exact English subject often has to be supplied from the situation.

After можно, Russian commonly uses the infinitive to express what is possible or allowed.

Pattern:

• Можно + infinitive

Examples:

• Можно войти? = May I come in?
• Можно сесть? = May I sit down?
• Можно присоединиться к нам? = May I join you?/Is it possible to join us?

So присоединиться stays in the dictionary-like infinitive form.

Присоединиться means to join, to attach oneself to, or to come along with.

The ending -ся is the reflexive marker. In many verbs, it does not translate literally as oneself, but it is simply part of the verb’s normal form.

So:

• присоединить = to attach/join something to something
• присоединиться = to join, to join in, to attach oneself

In this sentence, присоединиться is the natural verb for join.

The verb присоединиться requires the preposition к with the dative case.

So:

• к нам = to us
• literally, the phrase is something like to join to us

This is just how the verb works in Russian.

Compare:

• присоединиться к группе = to join the group
• присоединиться к друзьям = to join friends
• присоединиться к нам = to join us

Because к takes the dative case.

The pronoun changes like this:

• мы = we
• нас = us (accusative/genitive)
• нам = to us (dative)

Since присоединиться к... needs к + dative, you get:

• к нам = to us

Присоединиться is perfective. Its imperfective partner is присоединяться.

Here the perfective makes sense because joining is seen as a single completed action: to join (successfully, at a certain moment).

Compare:

• Можно присоединиться? = May I join? / Can I come join you?
• Я присоединяюсь would describe the process or repeated/habitual action, which is not what this sentence needs.

After можно, both aspects are possible in Russian depending on meaning, but here the perfective is the natural choice.

Yes, it is generally polite and natural.

Russian often uses можно + infinitive as a soft, polite way to ask permission:

• Можно войти?
• Можно спросить?
• Можно присоединиться к нам?

If you want to sound even more explicitly polite, you could also say:

• Можно мне присоединиться к вам? = May I join you?
• Можно к вам присоединиться?

• к нам = to us
• к вам = to you (plural or polite singular)

If you are asking to join the people you are speaking to, the most common version is:

• Можно присоединиться к вам? = May I join you?

К нам would usually be used when the group being joined includes the speaker, or in a context where us is the intended group.

So for many learners, к вам may feel more expected in the common situation of asking others if you may join them.

Yes. Russian word order is flexible.

Possible variants include:

• Можно присоединиться к нам?
• Можно к нам присоединиться?

Both are grammatical. The first is neutral and very common. The second puts slightly more focus on к нам.

Russian word order often changes for emphasis, rhythm, or style rather than basic grammar.

The stress is:

• мо́жно
• присоедини́ться
• к нам

A rough pronunciation guide:

• MOZH-na prisa-ye-di-NIT-sa k nam

A more careful breakdown:

• можно → MOZH-na
• присоединиться → pri-sa-ye-di-NIT-sa
• к нам → k NAM

The main stress in the long verb is on -ни́-: присоедини́ться.

Yes, potentially. Russian sentences with можно + infinitive can be slightly open-ended without context.

Depending on the situation, Можно присоединиться к нам could be understood as:

• a permission question,
• a general possibility question,
• or a polite suggestion/request involving joining the group.

In real conversation, context usually makes the intended meaning obvious.

Yes, but it sounds different in tone.

For example:

• Я хочу присоединиться к вам. = I want to join you.
• Я хотел(а) бы присоединиться к вам. = I would like to join you.

Compared with those, Можно присоединиться...? sounds more like asking permission and is often softer and more polite.