Nous préférons reporter la décision jusqu'à ce que la sœur de Marie voie l'appartement.

Préférons is the present tense: nous préférons = we prefer.

French often uses the present tense in places where English might also use the present:

• Nous préférons reporter la décision... = We prefer to postpone the decision...

If you wanted we will prefer, that would be nous préférerons, but that would sound unusual in this context.

Also note the spelling change:

• préférer
• nous préférons

The accent changes because of French pronunciation patterns in different verb forms.

No. Here reporter means to postpone, to put off, or to delay.

So:

• reporter la décision = to postpone the decision

This is a useful false friend for English speakers, because English report usually means to give information about something. In French, reporter often means move something to a later time.

Examples:

• reporter une réunion = to postpone a meeting
• reporter un voyage = to postpone a trip

After préférer, French commonly uses an infinitive when the subject of both verbs is the same.

Here, the subject is nous for préférons, and the people doing the postponing are also nous:

• Nous préférons reporter...
• literally: We prefer to postpone...

This is very similar to English:

• We prefer to postpone...

Jusqu'à ce que means until.

It introduces a clause describing the point in time up to which something continues or is delayed.

So:

• Nous préférons reporter la décision jusqu'à ce que...
• We prefer to postpone the decision until...

It is best learned as a fixed expression:

• jusqu'à ce que + subjunctive

Because jusqu'à ce que is a fixed conjunction in French. You should learn the whole phrase together.

It is not built freely each time as if you could just remove ce. Standard French is:

• jusqu'à ce que

After it comes a full clause:

• jusqu'à ce que la sœur de Marie voie l'appartement

So the short answer is: that is simply the correct expression.

Because jusqu'à ce que requires the subjunctive, and voie is the subjunctive form of voir.

Compare:

• Indicative: elle voit = she sees
• Subjunctive: qu'elle voie = that she see

In your sentence:

• jusqu'à ce que la sœur de Marie voie l'appartement

The subjunctive is used because the action is still pending or not yet realized at the moment of speaking.

It helps to memorize a few subjunctive forms of voir:

• que je voie
• que tu voies
• qu'il/elle/on voie
• que nous voyions
• que vous voyiez
• qu'ils/elles voient

So voie here is the 3rd person singular present subjunctive:

• la sœur de Marie voie = Marie's sister see

It may look unfamiliar at first because the ordinary present form is voit.

Standard French usually expresses possession between nouns with de:

• la sœur de Marie = Marie's sister
• literally: the sister of Marie

Using à this way is not standard in careful French here. For a learner, the safe pattern is:

• le livre de Paul = Paul's book
• la voiture de ma mère = my mother's car
• la sœur de Marie = Marie's sister

French often uses the definite article where English might also use the, especially when talking about something specific and known from context.

Here:

• la décision = the decision
• l'appartement = the apartment

This suggests that both speaker and listener know which decision and which apartment are being discussed.

Also note:

• l'appartement is just le appartement shortened to l'appartement because French avoids two vowel sounds together.

French normally does not use the future here. After jusqu'à ce que, French uses the subjunctive present, not a future form.

So French says:

• jusqu'à ce que la sœur de Marie voie l'appartement

English also often avoids will after until:

• until Marie's sister sees the apartment

So in this sentence, French and English are actually fairly similar.

Not really in a way you need to translate word-for-word here. In this expression, ce is part of the conjunction jusqu'à ce que.

Trying to translate each piece separately is not very helpful. The best approach is to learn:

• jusqu'à ce que = until
• followed by the subjunctive

So even though ce often means this/that/it in other contexts, here it is just part of the fixed grammar pattern.

Sœur means sister. Its spelling can look strange to English speakers because of œ.

A practical pronunciation tip:

• sœur is pronounced roughly like the vowel in French peur or heure
• it is not pronounced like English sewer

The œ is a standard French spelling in some words, and it is worth recognizing visually:

• sœur = sister
• cœur = heart
• œuf = egg

Yes, but it would mean something slightly different.

• jusqu'à ce que = until
• avant que = before

Your original sentence means the postponement lasts up to the moment when Marie's sister sees the apartment.

If you said:

• avant que la sœur de Marie voie l'appartement that would mean before Marie's sister sees the apartment, which focuses on an earlier point, not the endpoint expressed by until.

Both jusqu'à ce que and avant que are followed by the subjunctive.