Мы говорили со священником.

Because after the preposition с / со meaning with, Russian normally uses the instrumental case.

So:

• священник = priest (dictionary form, nominative)
• священником = with a priest / with the priest (instrumental)

This is a very common pattern:

• с другом = with a friend
• с братом = with a brother
• с учителем = with a teacher

So in Мы говорили со священником, the ending -ом shows the instrumental case.

Russian sometimes uses со instead of с to make pronunciation easier.

Here, с св... would be awkward because of the consonant cluster. So Russian prefers:

• со священником

This happens in other expressions too, for example:

• со мной = with me
• со всеми = with everyone

So со is not a different meaning from с here; it is just the smoother pronunciation.

It is the instrumental case.

The instrumental case is often used:

• after с / со meaning with
• for means or manner in some other constructions
• after certain verbs

In this sentence, the reason is simple: со + instrumental.

So:

• со священником = with a priest / with the priest

Говорили is past tense.

It is the past tense plural form of говорить.

Compare:

• я говорил / говорила = I spoke / I was speaking
• мы говорили = we spoke / we were speaking
• они говорили = they spoke / they were speaking

Russian past tense agrees with number and, in the singular, with gender. Since мы is plural, the form is говорили.

It can mean any of those, depending on context.

The verb говорить is imperfective, so говорили often suggests:

• an ongoing action: were speaking
• a repeated action: used to speak
• sometimes simply spoke in a general sense

So Мы говорили со священником could mean:

• We were talking with the priest
• We talked with the priest
• We used to talk with the priest

The wider context tells you which English translation fits best.

In Russian, говорить с кем-то means to talk with someone or to talk to someone.

So the person involved in the conversation is commonly expressed with с / со + instrumental:

• говорить с другом = talk with a friend
• говорить с врачом = talk with a doctor
• говорить со священником = talk with a priest

English often says talk to someone, but Russian very often uses a structure that literally looks more like talk with someone.

Russian has no articles.

So священником can mean:

• a priest
• the priest

You understand which one is meant from context.

That means Мы говорили со священником could be:

• We talked with a priest
• We talked with the priest

Both are possible unless the surrounding context makes one definite.

Because the subject is мы, which means we.

Russian verbs in the past tense agree with the subject in number:

• я говорил / говорила = I spoke
• ты говорил / говорила = you spoke
• он говорил = he spoke
• она говорила = she spoke
• мы говорили = we spoke
• они говорили = they spoke

Since мы is plural, the verb must be говорили.

Yes. Russian word order is more flexible than English word order.

The neutral order here is:

• Мы говорили со священником.

But you could also hear:

• Со священником мы говорили.
• Говорили мы со священником.

These versions may shift emphasis or sound more literary or contrastive, but the basic meaning stays the same because the cases show the grammatical roles.

The dictionary form is говорить.

That is the infinitive, meaning to speak or to talk.

Here is the chain:

• говорить = infinitive
• говорил / говорила / говорили = past tense forms

So when you look up говорили in a dictionary, you should search for говорить.

This is a very common question.

• говорить usually focuses on the process of speaking, conversation, or repeated speech
• сказать usually means to say something once, often as a completed act

So:

• Мы говорили со священником = We talked with the priest / We were speaking with the priest
• Мы сказали священнику... = We told the priest... / We said to the priest...

Notice that сказать often takes the person in the dative case:

• священнику = to the priest

But говорить с кем-то uses с / со + instrumental:

• со священником = with the priest

Roughly, it sounds like:

svya-SHEN-ni-kam

A few helpful points:

• свя sounds approximately like svya
• the stress is on -щен-: свяЩЕНником
• the final -ом is pronounced closer to -am in normal speech

The whole phrase:

• Мы говорили со священником

is roughly:

mɨ gava-REE-li sa svya-SHEN-ni-kam

That is only an approximation, but it can help as a starting point.