Drago mi je što ovog ljeta opet idemo na obalu.

That is a very common question. Drago mi je is an impersonal expression in Croatian.

Literally, it is something like:

• drago = dear / pleasant / glad
• mi = to me
• je = is

So the structure is closer to It is pleasant to me or It is dear to me, which Croatian uses to mean I’m glad.

This is why you do not say Ja sam drago. That would sound wrong. Croatian often uses this kind of structure for feelings and reactions.

Examples:

• Drago mi je. = I’m glad.
• Žao mi je. = I’m sorry.
• Dosadno mi je. = I’m bored.

Mi is the dative singular form of ja.

Croatian uses the dative in expressions like this to show the person experiencing the feeling.

So:

• Drago mi je = It is pleasant/glad to me
• Drago ti je = You are glad
• Drago mu je = He is glad
• Drago nam je = We are glad

This may feel unusual to an English speaker, because English usually makes the person the grammatical subject: I am glad. Croatian often does not.

Here što means that and introduces a subordinate clause:

• Drago mi je što... = I’m glad that...

So in this sentence:

• Drago mi je što ovog ljeta opet idemo na obalu.
• I’m glad that we’re going to the coast again this summer.

Important: što can mean different things in different contexts. For example, it can also mean what. But here it is a conjunction, not a question word.

Ovog ljeta is a very common way to say this summer in Croatian.

Here:

• ovog = genitive singular of ovaj
• ljeta = genitive singular of ljeto

So the phrase is in the genitive.

Croatian often uses the genitive in expressions of time, especially with seasons and parts of the year:

• ovog ljeta = this summer
• prošle zime = last winter
• iduće godine = next year

English speakers often expect a plain nominative or accusative, but Croatian frequently uses case forms in time expressions.

Yes, you can hear ovo ljeto as well, and it also means this summer.

In practice:

• ovog ljeta is very common and often feels a bit more neutral or standard in many contexts
• ovo ljeto is also widely used, especially in everyday speech

So both can be correct, but ovog ljeta is an especially useful pattern to learn because you will see the genitive of time very often.

Croatian often uses the present tense to talk about a planned or expected future event, especially when the context already makes the time clear.

Here the future is understood from ovog ljeta.

So:

• ovog ljeta idemo na obalu
  literally looks like this summer we go to the coast but really means
• this summer we’re going / we’re going to go to the coast

This is very natural in Croatian, just as English can say:

• We’re going to the coast this summer

even though the action is in the future.

Because Croatian usually does not need subject pronouns when the verb ending already shows who the subject is.

Here:

• idemo = we go / we are going

The ending -mo tells you the subject is we.

So mi idemo is possible, but mi is usually omitted unless you want to add emphasis or contrast.

For example:

• Idemo na obalu. = We’re going to the coast.
• Mi idemo na obalu, a oni ostaju doma. = We are going to the coast, and they are staying home.

Opet means again.

In this sentence:

• ovog ljeta opet idemo na obalu = this summer we’re going to the coast again

Croatian word order is fairly flexible, so opet can move around depending on emphasis. For example:

• Ovog ljeta opet idemo na obalu.
• Opet idemo na obalu ovog ljeta.

These versions are all understandable, but the original sounds very natural.

This is a case question.

With na, Croatian often makes a distinction between:

• movement toward a place → accusative
• location at/on a place → locative

So:

• na obalu = to the coast → movement, so accusative
• na obali = on/at the coast → location, so locative

Since the sentence is about going to the coast, Croatian uses na obalu.

Because Croatian uses different prepositions depending on how a place is conceptualized.

• u usually means into / in
• na often means onto / on / to, but it is also used idiomatically with many destinations

With obala in the sense of the coast / seaside area, Croatian normally says:

• ići na obalu = to go to the coast
• biti na obali = to be at the coast

So this is not just a literal on versus in issue. It is the normal Croatian preposition for this expression.

The basic form is obala, a feminine noun meaning coast or shore.

In the sentence, it appears as obalu, which is the accusative singular form.

So:

• nominative: obala
• accusative: obalu

It is accusative because it follows na with the idea of movement toward a destination:

• idemo na obalu = we’re going to the coast

In this sentence, što is the normal and natural choice after Drago mi je.

So:

• Drago mi je što... = natural
• Drago mi je da... = generally not the standard choice here

Learners often overuse da because it is a very common conjunction in Croatian, but certain expressions strongly prefer što. Drago mi je što... is one of those patterns worth memorizing as a whole.