Si faber hodie tectum reficit, familia hac nocte sine timore dormiet.

Si means if. It introduces the condition of the sentence: if the builder repairs the roof today...

This makes the whole sentence a conditional statement:

• condition: Si faber hodie tectum reficit
• result: familia hac nocte sine timore dormiet

Reficit is present indicative: repairs / is repairing.
Dormiet is future indicative: will sleep.

Latin can express an open, real condition this way, much like English:

• If the builder repairs the roof today, the family will sleep without fear tonight.

So the condition is stated with a present form, and the result is stated as future. This is a normal and understandable pattern.

Faber is a noun meaning craftsman, artisan, workman, or in some contexts builder or carpenter.

Its exact English translation depends on context. Because the sentence is about fixing a roof, builder or workman makes good sense here.

Grammatically, faber is nominative singular, so it is the subject of reficit.

Tectum is the direct object of reficit, so it is in the accusative singular.

The basic idea is:

• faber = the subject, the one doing the action
• tectum = the thing being repaired

So tectum reficit means repairs the roof.

Also, tectum is a neuter noun.

Not always. Tectum can mean:

• roof
• house
• dwelling

But in this sentence, because someone is repairing it and the family will then sleep safely, roof is the most natural meaning.

Hodie is an adverb meaning today.

Because it is an adverb, it does not change its form for case, number, or gender. It simply tells you when the action of reficit happens.

Hac nocte is in the ablative because Latin often uses the ablative of time when without a preposition.

So:

• hac nocte = on this night / tonight

English usually needs a preposition or an idiomatic expression, but Latin often does not.

Hac is the ablative feminine singular of hic, haec, hoc meaning this.
Nocte is the ablative singular of nox, noctis meaning night.

They agree with each other:

• feminine
• singular
• ablative

So hac nocte literally means on this night, which we usually translate more naturally as tonight.

The preposition sine means without, and it always takes the ablative case.

So:

• sine timore = without fear

Here timore is the ablative singular of timor.

Familia can mean more than just a modern nuclear family. In Latin it can refer to:

• a family
• a household
• all the people belonging to a house, including dependents or servants in some contexts

In this sentence, the family or the household both fit well.

Grammatically, familia is nominative singular and is the subject of dormiet.

Latin word order is more flexible than English because the endings show how the words function.

So Latin can say:

• Si faber hodie tectum reficit, familia hac nocte sine timore dormiet

Even though the order is different from standard English, the cases and verb endings make the relationships clear.

A more English-like order would still mean the same thing, for example:

• Si hodie faber tectum reficit, familia sine timore hac nocte dormiet

The original order is perfectly natural Latin.

Latin has no articles like English the or a/an.

So:

• faber can mean a builder or the builder
• tectum can mean a roof or the roof
• familia can mean a family or the family

You decide from the context which English article sounds best.

Yes, literally hac nocte means on this night. But in natural English, tonight is usually the best translation.

That is a common difference between literal Latin structure and idiomatic English translation.