Uvek perem ruke pre ručka.

Because Serbian often leaves out subject pronouns when the verb already makes the subject clear.

Perem means I wash, so ja is not necessary. The ending -em tells you it is first person singular.

So:

• Uvek perem ruke pre ručka. = I always wash my hands before lunch.
• Ja uvek perem ruke pre ručka. = also correct, but ja adds emphasis, like I always wash my hands before lunch.

Perem is the present tense, first person singular form of the verb prati, meaning to wash.

So:

• prati = to wash
• perem = I wash / I am washing

In this sentence, because of uvek meaning always, the present tense has a habitual meaning:

• Uvek perem... = I always wash...

It is not describing one action happening right now, but a regular habit.

Ruke is the form of ruka used here for hands.

• ruka = hand
• ruke = hands

In this sentence, ruke is the direct object, so it is in the accusative plural. For this noun, the accusative plural looks the same as the nominative plural.

So the sentence literally has:

• perem = I wash
• ruke = hands

Serbian normally uses the plural here because people usually wash both hands.

Because in Serbian, possessive words are often omitted with body parts when ownership is obvious.

So perem ruke naturally means I wash my hands, not just I wash hands in some vague sense.

This is very common in Serbian. For example:

• Perem ruke. = I wash my hands.
• Češljam kosu. = I comb my hair.
• Zatvorio je oči. = He closed his eyes.

You can say svoje ruke or moje ruke, but that usually sounds emphatic, contrastive, or unnatural in a simple everyday sentence.

Because the preposition pre requires the genitive case.

The base form is:

• ručak = lunch

But after pre, it changes to the genitive:

• pre ručka = before lunch

So this is a case-governed construction:

• pre + genitive

Other examples:

• pre škole = before school
• pre posla = before work
• pre večere = before dinner

Usually, pre is the normal word for before in the sense of earlier than.

• pre ručka = before lunch

Pred is a different preposition. It most basically means in front of, and it takes a different case, the instrumental.

• pred kućom = in front of the house

It can also be used in time expressions, but it does not work exactly the same way as pre. In a simple sentence like this, pre ručka is the most natural and standard choice for before lunch.

So for learners, the safest rule is:

• use pre + genitive for before in time

Yes. Serbian word order is more flexible than English word order.

The sentence:

• Uvek perem ruke pre ručka.

is a very natural, neutral order.

But you could also say:

• Pre ručka uvek perem ruke.

This puts more emphasis on before lunch.

You might also hear:

• Ruke uvek perem pre ručka.

This sounds more marked and emphasizes hands.

So the basic meaning stays the same, but word order can shift the focus or emphasis.

This is about aspect, which is very important in Serbian verbs.

• prati / perem = imperfective
• oprati / operem = perfective

Very roughly:

• imperfective looks at the action as a process, habit, or repeated activity
• perfective looks at it as a completed whole

Because this sentence describes a general habit with always, perem is a very natural choice.

• Uvek perem ruke pre ručka. = I always wash my hands before lunch.

If someone said Uvek operem ruke pre ručka, it could sound like they are emphasizing that they get the action done completely each time. That is possible in some contexts, but perem is the more neutral verb for a simple habitual statement like this.

Yes. Uvek is the normal Serbian word for always.

It usually goes near the beginning of the sentence, especially in simple statements:

• Uvek perem ruke pre ručka.

That placement sounds very natural.

Depending on region and standard variety, you may also see uvijek instead of uvek. The meaning is the same; the difference is mainly pronunciation and standard variety.