Planul său este clar.

Because -ul is the Romanian definite article attached to the end of the noun.

• plan = plan
• planul = the plan

Romanian usually puts the at the end of the noun instead of using a separate word like English does.

So:

• Planul său = his plan / the plan of his

Său means his in this sentence.

So:

• planul = the plan
• său = his
• este clar = is clear

Together: Planul său este clar. = His plan is clear.

Romanian has two common ways to say his:

• planul său
• planul lui

Both can mean his plan.

However, there is an important difference in style and usage:

• său/sa/săi/sale is the more traditional grammatical possessive form
• lui is very common in everyday speech and often sounds more natural in conversation

So Planul său este clar is perfectly correct, but in spoken Romanian many people would also say:

• Planul lui este clar.

Learners should recognize both.

In Romanian, possessives often come after the noun, especially in structures like this.

So Romanian says:

• planul său literally = the plan his

but in natural English we translate it as:

• his plan

This word order is normal in Romanian and should not be translated word-for-word.

It agrees with the thing owned, not with the owner.

That is a very important difference from English.

Here, the possessed noun is planul (plan), which is masculine singular, so Romanian uses său.

Compare:

• planul său = his/her plan → plan is masculine singular, so său
• cartea sa = his/her book → carte is feminine singular, so sa
• prietenii săi = his/her friends (masculine plural)
• ideile sale = his/her ideas (feminine plural)

So the form changes according to the noun being possessed.

Yes. By itself, său can mean his or her, depending on context.

So:

• Planul său este clar. can mean:
  • His plan is clear.
  • Her plan is clear.

Romanian often relies on context to show whose plan it is.

That is one reason speakers sometimes prefer lui (his) or ei (her) when they want to be very clear:

• Planul lui este clar. = His plan is clear.
• Planul ei este clar. = Her plan is clear.

Normally, Romanian does use the verb to be in sentences like this.

So:

• Planul său este clar. = correct

You usually would not say:

• Planul său clar. ✗

Romanian is not like Russian or some other languages where the present-tense is can often be omitted in ordinary sentences.

In informal speech, however, este is often shortened to e:

• Planul său e clar.

That is very common and natural.

Clar is an adjective meaning clear.

Here it describes planul and works as a predicate adjective after este:

• Planul său este clar. = His plan is clear.

In this sentence, clar is masculine singular, matching planul.

If the noun changed, the adjective would also change:

• Ideea sa este clară. = Her/His idea is clear.
• Planurile sale sunt clare. = His/Her plans are clear.

So yes, the adjective does change depending on gender and number.

Yes. Este is the 3rd person singular form of a fi (to be).

So it means:

• he/she/it is

Because Romanian verbs already show the subject, there is no separate subject pronoun here. Romanian does not need to say it is the way English does.

So the structure is simply:

• Planul = subject
• este = verb
• clar = adjective

Word-for-word, it looks a bit like that:

• Planul = the plan
• său = his
• este = is
• clar = clear

But that is only a literal gloss. The correct English translation is:

• His plan is clear.

When learning Romanian, it helps to notice the literal structure, but you should not try to reproduce it in English.

Său is roughly pronounced like suh-oo, but very quickly as one syllable.

The letter ă is a short central vowel, similar to the a in English sofa or about.

So:

• său ≈ suhw / suh-ooh compressed into one syllable

The exact sound may take practice, but the key point is that ă is not a normal English a sound.

Yes, Romanian word order is somewhat flexible, but the neutral, normal order here is:

• Planul său este clar.

Other orders are possible for emphasis or style, but they are less neutral:

• Clar este planul său.
• Este clar planul său.

A learner should treat Planul său este clar as the standard version.

A very natural conversational version would be:

• Planul lui e clar.

This uses:

• lui instead of său
• e instead of este

That said, Planul său este clar is still fully correct and useful to understand, especially in writing or more formal language.