في عطلة نهاية الأسبوع عندنا دعوة إلى بيت صديقتنا على الغداء.

Because Arabic often starts with a time expression to set the scene first.

• في = in / during / on
• عطلة نهاية الأسبوع = the weekend

So في عطلة نهاية الأسبوع means at the weekend / during the weekend.

Starting with the time phrase is very natural in Arabic, just like English can say:

• At the weekend, we have...
• This weekend, we have...

It does not mean the rest of the sentence is less important; it just gives the time first.

عطلة نهاية الأسبوع literally means something like the holiday/break of the end of the week, i.e. the weekend.

It is an iḍāfa structure, or construct phrase:

• عطلة = break / holiday
• نهاية = end
• الأسبوع = the week

So:

• نهاية الأسبوع = the end of the week
• عطلة نهاية الأسبوع = the weekend break

This kind of noun chaining is very common in Arabic.

This is because عطلة نهاية الأسبوع is an iḍāfa phrase.

In an iḍāfa:

• the first noun usually does not take ال
• the whole phrase gets its definiteness from the last noun

Since الأسبوع has ال, the whole expression becomes definite:

• نهاية الأسبوع = the end of the week
• عطلة نهاية الأسبوع = the weekend

So even without ال on عطلة, the whole phrase is understood as definite.

Arabic often expresses possession with عند + a pronoun, rather than with a verb like English have.

• عند basically means at / with
• عندنا literally means at us or with us

So:

• عندنا دعوة literally = At us there is an invitation
• natural English = We have an invitation

This is a very common Arabic pattern:

• عندي كتاب = I have a book
• عندها سيارة = She has a car
• عندنا وقت = We have time

Yes. It is a nominal sentence, which is very normal in Arabic.

Arabic does not always need a verb like to be or to have in the present tense. Instead, it can use a noun phrase or prepositional phrase.

Here the core idea is:

• عندنا دعوة = we have an invitation

There is no separate present-tense verb meaning have. The meaning is understood from the structure.

Here دعوة means an invitation.

It comes from the root related to calling/inviting, but in this context it refers to the thing itself: an invitation.

So:

• عندنا دعوة = we have an invitation

Because it is indefinite, it means an invitation, not the invitation.

If it were الدعوة, that would mean the invitation.

إلى بيت صديقتنا means to the house of our female friend, or more naturally, to our female friend’s house.

Breakdown:

• إلى = to
• بيت = house/home
• صديقتنا = our female friend

So the invitation is specifically to her house.

Arabic often uses to the house of X where English might simply say:

• to our friend’s
• to our friend’s house

Because صديقتنا is feminine.

• صديق = male friend
• صديقة = female friend
• صديقتنا = our female friend

The ending ـة marks the feminine form, and ـنا means our.

So:

• صديقتنا = our female friend
• صديقنا = our male friend

It has two parts:

• صديقة = female friend
• ـنا = our

When the pronoun suffix is attached, the word becomes:

• صديقتنا = our female friend

Notice that the ـة of صديقة changes in pronunciation when followed by a suffix. That is why you hear -t-:

• ṣadīqa on its own
• ṣadīqatunā / ṣadīqatnā in context

This is normal for words ending in ـة.

Yes, على often means on, but prepositions do not match perfectly from one language to another.

In this expression:

• على الغداء means for lunch or over lunch

It is a common Arabic way to indicate that the invitation is for a meal.

Similar expressions include:

• على الفطور = for breakfast
• على العشاء = for dinner

So you should learn على + meal as a set expression in contexts like invitations and visits.

In some contexts, yes, Arabic may use other prepositions, and speakers vary. But على الغداء is a very natural expression for an invitation involving lunch.

It gives the sense of:

• for lunch
• over lunch

So for a learner, دعوة ... على الغداء is a useful phrase to remember.

Arabic word order is often more flexible than English.

This sentence is arranged like this:

• في عطلة نهاية الأسبوع = time
• عندنا دعوة = what we have
• إلى بيت صديقتنا = where/to whose house
• على الغداء = for what occasion/meal

English might say:

• This weekend, we have an invitation to our friend’s house for lunch.

Arabic often places information in a slightly different order, but the sentence is still completely natural.

Yes, Arabic often allows some movement of phrases for style or emphasis.

For example, a speaker could rearrange parts and still be understood. But the given order is natural and clear:

• time first
• then the main idea
• then destination
• then meal

So while the word order is somewhat flexible, the original sentence is a good standard model.

A very helpful way to study it is in chunks:

• في عطلة نهاية الأسبوع = at the weekend
• عندنا دعوة = we have an invitation
• إلى بيت صديقتنا = to our female friend’s house
• على الغداء = for lunch

If you learn these as ready-made pieces, you can easily make new sentences, such as:

• في عطلة نهاية الأسبوع عندنا زيارة إلى بيت خالتي.
• عندنا دعوة إلى بيت صديقنا على العشاء.

That is often more useful than translating word by word every time.