Al juny, la meva filla acaba l'escola, i al juliol anem a la platja si no hi ha tempesta.

Because Catalan often uses a + article + month to mean in a month.

• al = a + el
• al juny = in June
• al juliol = in July

So this is a very normal time expression in Catalan.

Yes. Catalan often puts time expressions at the beginning, but they can also appear later.

For example:

• Al juny, la meva filla acaba l'escola.
• La meva filla acaba l'escola al juny.

Both are possible. Putting Al juny first gives the time more emphasis and helps frame the sentence right away.

In standard Catalan, possessives usually go with a definite article.

So Catalan normally says:

• la meva filla
• el meu pare
• els nostres amics

English does not use the article here, but Catalan usually does. So la meva filla is the normal standard pattern.

They are both in the present indicative:

• acaba = she finishes / she is finishing
• anem = we go

In this sentence, the present is being used for a future meaning, because the time expressions make the future clear:

• Al juny...
• al juliol...

This is very common in Catalan, just as English can say In July we go to the beach for a planned future event.

It could. Catalan often uses the present for planned, expected, or scheduled future actions when the time is already clear.

So these are both possible:

• Al juny, la meva filla acaba l'escola.
• Al juny, la meva filla acabarà l'escola.

And:

• Al juliol anem a la platja.
• Al juliol anirem a la platja.

Using the present often sounds natural and straightforward.

Literally it means finishes school, but in this context it most likely means school ends for her in June or she finishes the school year in June.

Depending on context, acabar l'escola can mean different things, such as:

• finishing school for the year
• finishing school permanently
• finishing classes

Here, because of Al juny, the most natural reading is that school ends in June.

Yes, very different.

• acabar l'escola = to finish school
• acabar de + infinitive = to have just done something

For example:

• La meva filla acaba l'escola = My daughter finishes school
• La meva filla acaba de sortir = My daughter has just left

So in your sentence, acaba means finishes, not has just.

Because the feminine singular article la becomes l' before a vowel.

So:

• la filla
• la platja
• l'escola

This is just the normal apostrophe rule in Catalan.

Because anar normally takes a before a destination:

• anar a casa
• anar a l'escola
• anar a la platja

And la platja keeps its article. There is no contraction here because a + la stays a la.

Only some combinations contract, such as:

• a + el = al
• de + el = del

So:

• al juny
• a la platja

hi ha is the normal Catalan expression for there is / there are.

So:

• hi ha tempesta = there is a storm
• no hi ha tempesta = there is no storm

The hi is part of this fixed existential construction, haver-hi. Even when English just uses there, Catalan uses hi ha.

Yes. In modern standard Catalan, hi ha is used for both singular and plural in the present.

So you get:

• hi ha una tempesta = there is a storm
• hi ha tempestes = there are storms

So if the sentence were plural, it could be:

• si no hi ha tempestes = if there are no storms

Because si no means if not or if there isn’t.

Here:

• si no hi ha tempesta = if there is no storm

But sinó is a different word. It usually means but rather or except.

Compare:

• Si no plou, anirem a la platja. = If it doesn’t rain, we’ll go to the beach.
• No anem a la muntanya, sinó a la platja. = We’re not going to the mountains, but rather to the beach.

This is a very common spelling point for learners.

Because Catalan often uses a bare noun after hi ha when talking about a general situation or condition.

So:

• hi ha tempesta
• hi ha boira
• hi ha problemes

This sounds like talking about the presence of that condition in general.

If you wanted to make it more explicitly countable, you could also say:

• hi ha una tempesta

But in this sentence, tempesta without an article sounds natural.

Not always. In Catalan, a comma before i is often omitted, especially in shorter sentences.

So this would also be natural:

• Al juny la meva filla acaba l'escola i al juliol anem a la platja si no hi ha tempesta.

The comma in your sentence helps separate the two main parts and can make the sentence easier to read. So it is understandable and acceptable, but not absolutely required in many contexts.

A rough English-friendly guide is:

• juny ≈ zhoony, with zh like the s in measure, and ny like the ny in canyon
• juliol ≈ zhoo-lee-OL

A few details:

• The j in many varieties of Catalan sounds like zh.
• juny has the ny sound, like Spanish ñ.
• juliol is stressed on the last syllable: -ol.

Exact pronunciation varies a bit by dialect, but those approximations are a good start.