Restat ut magister auctionis auctionem praedicet.

Together, restat ut means something like it remains for ... to ... or all that remains is that ....

• restat = it remains
• ut introduces the action that still has to happen

So Latin is not just saying that something remains in a general sense; it is pointing to the next or final action still to be done.

Because after restat ut, Latin normally uses the subjunctive.

This is a standard construction: the ut-clause is not a plain statement of fact, so Latin does not use the indicative. Instead, it presents the action as the thing that remains to be done.

So:

• praedicat would be indicative: he announces
• praedicet is subjunctive: that he should announce / for him to announce

The present subjunctive also fits well with restat in the present tense.

Not really, or at least not in the usual purpose-clause sense.

A learner often first meets ut as meaning so that or in order that, but here that is not the best way to understand it. In this sentence, ut introduces a clause completing the idea of restat.

So here ut is better understood as:

• that
• or, in more natural English, for ... to ...

In other words, this is not mainly a purpose clause; it is a clause telling you what remains.

The subject is magister auctionis.

You can tell because:

• magister is nominative singular
• it is the person who performs the action of praedicet

So the one who is to do the announcing is the magister auctionis.

Yes, magister can mean teacher, but it has a wider range than the English word teacher.

Its basic sense is more like:

• master
• chief
• person in charge
• director
• sometimes teacher

So in magister auctionis, it means the person in charge of the auction, not a classroom teacher. In context, that is naturally understood as the auctioneer or the official running the sale.

Because they are in different cases and doing different jobs.

They both come from the noun auctio, auctionis.

• auctionis = genitive singular
  This means of the auction and depends on magister
• auctionem = accusative singular
  This is the direct object of praedicet

So:

• magister auctionis = the master/manager of the auction
• auctionem praedicet = announce the auction

This is a good example of how Latin uses case endings to show function.

The dictionary form is auctio, auctionis.

That tells you:

• nominative singular: auctio
• genitive singular: auctionis

From that stem you get other forms, including:

• auctionem = accusative singular

So if you were looking it up, you would not look for auctionem as the headword; you would look for auctio.

Here praedicare means to proclaim publicly, announce, or call out.

In an auction context, it refers to the public verbal announcing connected with the sale. So it is not about predicating in the grammar-logic sense, even though the English word predicate is historically related.

In this sentence, think of praedicet as announce or proclaim, not as anything technical from English grammar.

Because Latin word order is flexible, and this order is very natural.

The sentence is arranged like this:

• Restat — first, to set up the main idea: it remains
• ut — introducing the subordinate clause
• magister auctionis — the subject of that clause
• auctionem — the object
• praedicet — the verb, placed at the end

Putting the verb at the end of the clause is very common in Latin. English relies heavily on word order for grammar, but Latin relies much more on case endings, so the order can be moved around for style or emphasis.

Because restat is being used impersonally.

Latin often uses a third-person singular verb where English would say it:

• restat = it remains

That it does not refer to a concrete thing. It is just the normal impersonal way of expressing the idea. English does the same kind of thing in sentences like it is necessary or it remains to be seen.

Latin sometimes does use restat with an infinitive, especially in simpler expressions such as restat dicere = it remains to say.

But when Latin wants to express the remaining action as a fuller clause, especially with an explicit subject, ut + subjunctive is very natural.

So:

• restat dicere = it remains to say
• restat ut magister auctionis auctionem praedicet = it remains for the auctioneer to announce the auction

The ut-clause gives Latin a clear way to state exactly who is to do the action.

It is inside the ut clause.

The clause introduced by ut is:

ut magister auctionis auctionem praedicet

Within that clause:

• magister auctionis = subject
• auctionem = object
• praedicet = verb

So the whole subordinate clause tells you what remains to happen.