Spotkanie kończy się o siódmej.

In this sentence, się is part of the verb expression kończyć się, which means to end, to come to an end, or to be over.

Compare:

• kończyć = to end/finish something
• kończyć się = to end, to finish, to come to an end

So:

• Kończę pracę = I am finishing the work
• Praca się kończy = The work is ending

In English, we often use the same verb for both ideas, but Polish often distinguishes them with się.

Because when Polish gives the time of day after o meaning at, it normally uses an ordinal number, not a cardinal number.

So Polish says:

• o pierwszej = at one
• o drugiej = at two
• o siódmej = at seven

This comes from an understood word:

• o siódmej godzinie = at the seventh hour

In everyday speech, godzinie is omitted, but the grammar stays the same.

It is in the locative singular.

The preposition o usually requires the locative when it means about or when it is used in time expressions like this one.

So:

• o siódmej
• o ósmej
• o dziesiątej

All of these are locative forms.

Because siódmej is not agreeing with spotkanie.

It is agreeing with the implied noun godzina, which is feminine.

So the full underlying structure is:

• Spotkanie kończy się o siódmej godzinie

Since godzina is feminine, the ordinal is feminine too:

• pierwsza godzina → o pierwszej
• siódma godzina → o siódmej

So the gender here has nothing to do with spotkanie.

Normally, no. In standard Polish, that sounds incomplete or wrong for this meaning.

• Spotkanie kończy się o siódmej = The meeting ends at seven

Without się, kończy is usually understood as a transitive verb, so it would suggest that the meeting is ending something, which does not fit here.

So if you mean that the meeting itself comes to an end, use kończy się.

Because the subject spotkanie is singular, and the verb is in the 3rd person singular.

• spotkanie = meeting, singular
• kończy się = ends

If the subject were plural, the verb would change:

• Spotkania kończą się o siódmej = The meetings end at seven

In the present tense, Polish verbs agree with the subject in number and person.

This is a question of aspect.

• kończyć się = imperfective
• skończyć się = perfective

In this sentence:

• Spotkanie kończy się o siódmej = The meeting ends at seven / is ending at seven

This is a normal way to talk about a schedule or a general fact.

But:

• Spotkanie skończy się o siódmej = The meeting will end at seven

Because perfective verbs in Polish do not have a true present tense, their present-looking forms usually have future meaning.

So:

• kończy się = present / habitual / scheduled
• skończy się = future completed event

No, Polish word order is fairly flexible.

The neutral order is:

• Spotkanie kończy się o siódmej

But you could also say:

• O siódmej kończy się spotkanie
• Kończy się o siódmej spotkanie

The last one is less neutral and more stylistically marked, but still possible in the right context.

Changing the order usually changes emphasis, not the basic meaning.

For example:

• Spotkanie kończy się o siódmej = neutral statement
• O siódmej kończy się spotkanie = emphasis on the time

You would usually say:

• O której kończy się spotkanie?

Literally, this is At which hour does the meeting end?

Useful pattern:

• O której zaczyna się spotkanie? = What time does the meeting start?
• O której kończy się spotkanie? = What time does the meeting end?

So o której is the standard way to ask for a clock time.

Just add nie before the verb:

• Spotkanie nie kończy się o siódmej.

This means:

• The meeting does not end at seven

In Polish, nie is placed before the finite verb:

• kończy się → nie kończy się

A rough English-friendly guide is:

• Spotkanie ≈ spot-KAH-nye
• kończy się ≈ KON-chih shye
• o siódmej ≈ o SHOOD-may

A few pronunciation notes:

• ń is a soft n
• się sounds roughly like shye
• ó sounds like u
• sz sounds like English sh
• cz sounds like English ch, but harder

So the whole sentence is approximately:

• spot-KAH-nye KON-chih shye o SHOOD-may

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