He pensat que podem fer la festa a casa meva si plou.

Yes. He pensat is the present perfect in Catalan:

• he = I have
• pensat = past participle of pensar (to think)

So literally it is I have thought. In real usage, though, Catalan often uses this tense in places where English might say:

• I thought...
• I've thought that...
• I was thinking that...

In this sentence, He pensat que... sounds like introducing an idea or suggestion: I thought that... / I was thinking that...

Because Catalan usually drops subject pronouns when they are not needed.

The verb form already tells you who the subject is:

• he = I have
• has = you have
• ha = he/she/it has
• etc.

So He pensat already clearly means I have thought / I thought. Adding jo is possible, but it usually adds emphasis or contrast:

• Jo he pensat... = I thought..., as opposed to someone else.

Que introduces the clause that follows, just like that in English:

• He pensat que podem... = I thought that we can/could...

In Catalan, que is usually kept in this kind of sentence. English often drops that, but Catalan is less likely to omit que here. So He pensat podem fer... would sound wrong.

Podem is the present tense of poder (to be able to / can):

• podem = we can

Catalan often uses the present tense for a real, practical suggestion about the future:

• podem fer la festa... = we can have the party...

If you said podríem, that would mean we could, and it would sound a bit more tentative, polite, or hypothetical.

So the difference is roughly:

• podem = a straightforward suggestion
• podríem = a softer or more tentative suggestion

Both are possible in many contexts, but podem fits a confident, practical idea.

Catalan often uses fer (to do / to make) in expressions where English uses have, hold, or throw.

So:

• fer una festa = to have/throw a party
• fer la festa = to have the party (a specific party)

This is normal Catalan usage. Even though it may feel literal to an English speaker, fer is the natural verb here.

Because la festa refers to a specific party that both speaker and listener already know about.

• una festa = a party in general, any party
• la festa = the party, a particular one

So this sentence is talking about an already known event, not introducing a new idea like let’s have some party.

A casa meva is the natural, idiomatic way to say at my house or at my place.

It is a very common Catalan expression:

• a casa meva = at my house / at my place
• a casa teva = at your house
• a casa seva = at his/her/their house

Although a la meva casa may be understandable, it is usually less natural in this context. It sounds more like talking about the physical house itself, while a casa meva is the standard way to refer to someone’s home as a place.

In the fixed expression casa meva, the possessive comes after the noun. This is just the normal idiomatic pattern in this expression:

• casa meva
• casa teva
• casa seva

You can also say la meva casa in other contexts, but that is not the most natural choice here. In this sentence, a casa meva is the standard everyday wording.

Because after si (if) in a real condition, Catalan normally uses the present indicative, even when the meaning is about the future.

So:

• si plou = if it rains

This works like English:

• if it rains
  not usually
• if it will rain

So si plou is exactly what you expect in Catalan for a future possibility.

Catalan does not use a dummy subject like English it with weather verbs.

So:

• plou = it rains / it is raining
• neva = it snows
• fa fred = it is cold

There is no separate word for it here. The verb stands alone.

Yes, absolutely. That version is very natural too.

Both are correct:

• He pensat que podem fer la festa a casa meva si plou.
• He pensat que, si plou, podem fer la festa a casa meva.

The difference is mostly about focus and word order, not basic meaning.

• ...a casa meva si plou puts the condition at the end
• ...si plou, podem... highlights the condition earlier

Catalan word order is fairly flexible, especially with clauses like si plou.