Η πεθερά μου μένει κοντά μας και ο πεθερός μου έρχεται συχνά για καφέ.

They are the definite articles the.

• η = feminine singular nominative
• ο = masculine singular nominative

So:

• η πεθερά μου = my mother-in-law
• ο πεθερός μου = my father-in-law

Greek uses the definite article much more regularly than English, especially with family members and other specific people.

Because Greek usually puts these unstressed possessive forms after the noun.

So Greek says:

• η πεθερά μου = literally the mother-in-law my
• ο πεθερός μου = literally the father-in-law my

This is completely normal Greek word order.

The same pattern appears with:

• το σπίτι μου = my house
• η αδερφή μου = my sister

They mean:

• πεθερά = mother-in-law
• πεθερός = father-in-law

These are standard family terms for your spouse’s parents.

μένει is the 3rd person singular present of μένω.

So:

• μένω = I stay / I remain / I live
• μένει = he/she stays / remains / lives

In this sentence, because the subject is η πεθερά μου, it means she lives.

A useful point: μένω can mean both stay and live, and the context tells you which one is meant.

Because of the context κοντά μας.

When Greek says:

• μένω κάπου

it often means live somewhere.

So:

• μένει κοντά μας = she lives near us

If the context were different, μένω could mean stay or remain, but here live is the natural reading.

κοντά μας is the normal, natural way to say near us.

With words like κοντά, Greek very often uses the short weak pronoun directly:

• κοντά μου = near me
• κοντά σου = near you
• κοντά μας = near us

κοντά σε εμάς is possible, but it sounds more emphatic or contrastive, like near us, not near them.

So in an ordinary sentence, κοντά μας is the best choice.

They are genitive weak pronouns.

In Greek, the genitive is often used for possession:

• μου = my / of me
• μας = our / of us

So:

• η πεθερά μου literally contains a genitive idea: the mother-in-law of me
• κοντά μας uses the same short pronoun form after κοντά

This is one reason these little words are so common in Greek.

έρχεται is the 3rd person singular present of έρχομαι, which means I come.

So:

• έρχομαι = I come
• έρχεται = he/she comes

It looks like a middle/passive form because έρχομαι is one of those Greek verbs that has middle/passive endings but an active meaning. So έρχεται does not mean is being come or anything passive like that. It simply means comes.

Here it means usually / habitually.

That is especially clear because of συχνά = often.

So:

• ο πεθερός μου έρχεται συχνά = my father-in-law often comes

In Greek, the present tense can describe:

• what is happening now
• what happens regularly
• general facts

Here it is a habitual action.

συχνά is an adverb meaning often, and its position is fairly flexible.

In this sentence:

• ο πεθερός μου έρχεται συχνά για καφέ

That is very natural.

You could also hear:

• ο πεθερός μου συχνά έρχεται για καφέ
• συχνά ο πεθερός μου έρχεται για καφέ

But the original version is the most neutral and natural in everyday Greek.

για καφέ literally means for coffee, but in natural English it often means something like:

• for coffee
• to have coffee
• for a coffee visit

It is a very common Greek expression.

Greek often leaves out the article in set phrases like this, so για καφέ sounds natural and idiomatic.

If you say:

• για έναν καφέ

that sounds more like for a coffee / for one coffee, a bit more specific.

Yes, Greek can do either, depending on structure.

In your sentence, each noun has its own possessive:

• η πεθερά μου
• ο πεθερός μου

That is perfectly natural and very clear.

Greek could also combine them like this:

• η πεθερά και ο πεθερός μου

That usually means my mother-in-law and father-in-law.

So both patterns are possible. Repeating μου can make the sentence feel a little more balanced or explicit.

Greek word order is more flexible than English, but not random.

The original sentence is neutral and natural:

• Η πεθερά μου μένει κοντά μας και ο πεθερός μου έρχεται συχνά για καφέ.

You could move some elements for emphasis, especially συχνά, but the original order is what a learner should aim for first.

A good rule: learn the neutral version first, then notice how Greek shifts word order for emphasis later.