Regina dicit se sacerdotem et vicinas quoque invitare, quia omnes laetas videre vult.

A helpful way to break it up is:

• Regina dicit = The queen says
• se sacerdotem et vicinas quoque invitare = that she is inviting the priestess and the neighbors too
• quia = because
• omnes laetas videre vult = she wants to see them all happy

So the main verb of the whole sentence is dicit.
Inside what she says, the key infinitive is invitare.
Then quia introduces the reason for that statement.

Se is the reflexive pronoun. It refers back to the subject of the main verb, here regina.

So:

• Regina dicit se invitare = The queen says that she is inviting
• Regina dicit eam invitare would mean The queen says that she is inviting her or that she invites her, referring to some other woman, not the queen herself

In other words, Latin uses se when the person inside the reported statement is the same as the subject of the reporting verb.

Because Latin often expresses reported speech or thought with an accusative-and-infinitive construction rather than with a that-clause like English.

English:

• The queen says that she invites...

Latin:

• Regina dicit se ... invitare

Here:

• se = the subject of the reported statement
• invitare = the verb of the reported statement

This is one of the most important Latin patterns after verbs like:

• dicit = says
• putat = thinks
• scit = knows
• audit = hears

Se is in the accusative case.

That may feel strange at first, because in English the subject of a clause is not in an object form. But in Latin indirect statement, the subject of the infinitive goes into the accusative.

So in:

• Regina dicit se invitare

the word se is not the direct object of dicit.
It is the subject of invitare inside the indirect statement.

That is why learners often call this construction accusative + infinitive.

It looks that way because sacerdos, sacerdotis is a third-declension noun, and its accusative singular is sacerdotem.

The form itself does not tell you whether the priest is male or female. Sacerdos can be used for either sex, depending on context.

Here, the later phrase omnes laetas strongly suggests that the people being referred to are feminine, so sacerdotem is best understood here as a priestess.

So the important point is:

• -em here is just the normal accusative singular ending of a third-declension noun
• it is not a special masculine ending

Latin often uses an adjective as a noun when the meaning is clear.

So vicinas literally means something like:

• the neighboring women
• or simply the neighbors (female)

This is very common in Latin. English does something similar sometimes, but Latin does it much more freely.

So here vicinas is functioning as a noun: the female neighbors.

Quoque means also or too.

It usually comes after the word it especially emphasizes.

So:

• vicinas quoque = the neighbors too / the neighbors also

That placement is very normal in Latin.
English often puts too at the end, but Latin commonly places quoque right after the word it goes with.

Compare:

• sacerdotem quoque = the priestess too
• vicinas quoque = the neighbors too

Because they go together.

• omnes = all
• laetas = happy

Here laetas agrees with omnes in:

• number: plural
• gender: feminine
• case: accusative

So the phrase means:

• all of them happy
• everyone happy
  more literally, all [the women] happy

The feminine plural makes sense because the people mentioned earlier are understood as women.

If the group were masculine or mixed, Latin would normally use:

• omnes laetos

instead.

Yes, laetas describes omnes.

The phrase omnes laetas videre means:

• to see them all happy

Here laetas is a predicate adjective with omnes after a verb of perception (videre).

You can think of it like English:

• I see them happy
• more naturally, I see that they are happy

Latin often allows this direct pattern with verbs like videre.

You might wonder whether Latin really means omnes laetas esse. That would be a slightly different construction, an indirect statement: to see that all are happy. But here videre works directly with omnes laetas: to see all of them in a happy state.

So yes, laetas belongs with omnes, but you do not have to assume an omitted esse.

Because vult goes with regina, not with omnes.

The subject of vult is still the queen:

• Regina ... vult = The queen wants

What does she want?

• omnes laetas videre = to see everyone happy

So:

• regina = subject of dicit and vult
• omnes = object of videre

That is why vult is singular.

Because Latin word order is much more flexible than English word order. Latin relies heavily on endings, so the grammatical roles are often clear even when the order changes.

In this sentence, the order helps emphasis and flow:

• Regina dicit puts the speaker first
• se ... invitare keeps the indirect statement together
• vicinas quoque lets quoque follow the word it emphasizes
• quia omnes laetas videre vult saves the important idea vult for the end of the clause

A very literal English-style order would sound unnatural in Latin. Latin prefers an order that highlights meaning, balance, and emphasis rather than sticking to one fixed pattern.

Quia means because and introduces a reason:

• quia omnes laetas videre vult = because she wants to see them all happy

This explains why the queen says she is inviting these people.

So the logic is:

• she says she is inviting them
• because she wants to see them all happy

This is a straightforward causal clause with quia.