Ljeti radije pijem limunadu nego sok.

Ljeti means in summer or during the summer. It is a common adverb used for seasons and times of year.

U ljeto can also be understood, but ljeti is usually the more natural and idiomatic choice when speaking generally.

A simple approximation is LYEH-tee.

The lj is treated as one sound in Croatian, not as a separate l plus j. For an English speaker, it is roughly similar to the lli sound many people use in million, though not exactly the same.

Radije means rather or preferably, and in this sentence it gives the idea of I prefer to drink...

So radije pijem is literally something like I more gladly drink, but the natural English meaning is I’d rather drink or I prefer to drink.

Pijem is the 1st person singular present tense of piti (to drink).

So:

• pijem = I drink

Croatian verbs usually show the subject in the ending, so the pronoun ja (I) is not needed.

Because Croatian normally leaves out subject pronouns when they are already clear from the verb ending.

Since pijem already means I drink, adding ja would usually only be for emphasis:

• Ja pijem = I drink / I’m the one who drinks

In a neutral sentence, just pijem is enough.

Because limunadu is the accusative singular form. It is the direct object of pijem.

The dictionary form is:

• limunada = lemonade

But after a verb like drink, Croatian uses the accusative:

• pijem limunadu = I drink lemonade

For many feminine nouns ending in -a, the accusative singular ends in -u.

Because sok is a masculine inanimate noun, and for those nouns the accusative singular is usually the same as the nominative singular.

So:

• sok = nominative
• sok = accusative

That is why you get:

• pijem sok

But with a feminine noun like limunada, the accusative changes:

• limunada → limunadu

Nego means than or rather than in this kind of comparison.

With radije, Croatian commonly uses this pattern:

• radije ... nego ... = rather ... than ...

So:

• radije pijem limunadu nego sok means
• I’d rather drink lemonade than juice

Because Croatian often leaves out repeated words when they are obvious.

The full idea is:

• Radije pijem limunadu nego pijem sok

But repeating pijem sounds unnecessary here. So Croatian normally says:

• radije pijem limunadu nego sok

This is very natural.

Because Croatian does not have articles like English a/an and the.

So nouns like limunadu and sok appear without articles, and the exact meaning depends on context:

• limunadu can mean lemonade, a lemonade, or the lemonade
• sok can mean juice, a juice, or the juice

Because this sentence expresses a general habit or preference, not one completed action.

Piti is the imperfective verb to drink, which is what Croatian normally uses for repeated, habitual, or general actions:

• Ljeti radije pijem... = In summer, I prefer to drink...

A perfective verb such as popiti would suggest a completed act, more like drink up or finish drinking, which does not fit this sentence well.

Yes. Croatian word order is fairly flexible, although some versions sound more natural than others.

The original sentence:

• Ljeti radije pijem limunadu nego sok.

is very natural.

You can move words for emphasis, for example:

• Radije ljeti pijem limunadu nego sok.
• Limunadu ljeti radije pijem nego sok.

The core meaning stays similar, but the emphasis changes. The original version is a good neutral model to learn.