O kadar inatçı olma; bazen başkasının fikrini dinlemek daha iyi olur.

Here o kadar means so or that much/that degree.

So:

• o kadar inatçı olma = don’t be so stubborn

Literally, o kadar is something like that much or to that extent, but in everyday Turkish it often works as an intensifier before an adjective.

Examples:

• O kadar yorgunum. = I’m so tired.
• O kadar pahalı ki... = It’s so expensive that...

In your sentence, it is not literally pointing to a physical amount. It just strengthens inatçı.

Olma is the negative informal singular imperative of olmak (to be / to become).

Breakdown:

• ol = be
• olma = don’t be

So:

• inatçı ol = be stubborn
• inatçı olma = don’t be stubborn

This is addressed to one person in an informal way.

If you wanted the polite/plural form, you would say:

• O kadar inatçı olmayın.

In Turkish, many adjectives can be used with olmak to mean to be or to become in context.

So:

• inatçı = stubborn
• inatçı olmak = to be stubborn

This is very normal Turkish structure.

Other examples:

• mutlu olmak = to be happy
• sessiz olmak = to be quiet
• dikkatli olmak = to be careful

In the imperative, inatçı olma is simply don’t be stubborn.

It is mainly an adjective meaning stubborn, but like many Turkish adjectives, it can also function like a noun depending on context.

In this sentence, it is adjectival:

• inatçı olma = don’t be stubborn

But you can also hear:

• O çok inatçı. = He/She is very stubborn.
• Bir inatçıyla tartışmak zor. = It’s hard to argue with a stubborn person.

So Turkish often lets one word do both jobs, depending on how it is used.

Başkasının comes from başkası, which means someone else / another person, plus the genitive ending.

Breakdown:

• başka = other / another
• başkası = someone else / another one
• başkasının = someone else’s

Why the genitive? Because it is linked to a possessed noun:

• başkasının fikri = someone else’s opinion

This is a very common Turkish pattern:

• Ali’nin kitabı = Ali’s book
• öğretmenin arabası = the teacher’s car
• başkasının fikri = someone else’s opinion

You may also hear başka birinin fikri, which means nearly the same thing.

This is because fikir is one of the words that often drops a vowel when a vowel-initial suffix is added.

Breakdown:

• base word: fikir = opinion / idea
• fikri = his/her opinion or the opinion in a possessed form
• fikrini = his/her opinion
  • accusative

More precisely here:

• başkasının fikri = someone else’s opinion
• başkasının fikrini = someone else’s opinion as the definite object of dinlemek

So the form is not fikirini in standard Turkish here; it becomes fikrini.

This kind of vowel loss also happens in some other words, for example:

• şehir → şehri
• akıl → aklı

Because it is doing two jobs at once.

First, it is part of a possessive construction:

• başkasının fikri = someone else’s opinion

Here the possessed noun fikir gets a possessive ending.

Then, inside the phrase başkasının fikrini dinlemek, that noun is also the specific object of dinlemek (to listen to), so it takes the accusative too.

So:

• başkasının = someone else’s
• fikrini = his/her opinion
  • accusative object marker

That is why Turkish stacks these endings.

A useful way to understand it is:

• fikri = his/her opinion
• fikrini = his/her opinion as the thing being listened to

Because in this sentence, başkasının fikrini dinlemek functions as a whole verbal noun / infinitive phrase, basically like listening to someone else’s opinion.

It is the thing being talked about as a general action:

• Bașkasının fikrini dinlemek daha iyi olur.
• Listening to someone else’s opinion is/would be better.

The bare infinitive -mek / -mak is often used this way.

By contrast, dinlemeyi would usually appear when that infinitive phrase is itself the object of another verb:

• Başkasının fikrini dinlemeyi tercih etmelisin.
• You should prefer listening to someone else’s opinion.

So in your sentence, dinlemek is the natural form.

Literally, daha iyi olur means something like it becomes/will be better or it would be better.

In natural English, it often translates best as:

• it’s better
• it would be better

The verb olur is the aorist form of olmak. In Turkish, the aorist is often used for:

• general truths
• habits
• polite suggestions
• softened advice

So:

• bazen başkasının fikrini dinlemek daha iyi olur
  = sometimes it’s better to listen to someone else’s opinion = sometimes listening to someone else’s opinion would be better

This sounds less direct and a bit more advisory than a hard command.

Bazen means sometimes.

It shows that the speaker is not saying you should always follow other people’s opinions. Instead, the idea is:

• at least in some situations, listening to someone else is the better choice

So the sentence is softer and more reasonable than:

• Bașkasının fikrini dinlemek daha iyi olur. = Listening to someone else’s opinion is better.

Adding bazen makes it:

• Sometimes listening to someone else’s opinion is better.

The semicolon separates two closely related parts:

1. O kadar inatçı olma
2. bazen başkasının fikrini dinlemek daha iyi olur

This works very much like English punctuation. The first part is a command, and the second part explains or justifies it.

You could think of it as:

• Don’t be so stubborn; sometimes it’s better to listen to someone else’s opinion.

A comma is sometimes possible in informal writing, but the semicolon makes the relationship clearer.

It is informal singular, because of olma.

That means the speaker is talking to:

• one person
• in a familiar or direct way

If you wanted a more polite or plural version, you would say:

• O kadar inatçı olmayın; bazen başkasının fikrini dinlemek daha iyi olur.

So the rest of the sentence is neutral, but the imperative form tells you the level of formality.

Yes, Turkish word order is flexible, but the given version is very natural.

Current sentence:

• O kadar inatçı olma; bazen başkasının fikrini dinlemek daha iyi olur.

This sounds smooth and balanced.

You could move things around for emphasis, for example:

• Bazen başkasının fikrini dinlemek daha iyi olur; o kadar inatçı olma.

That changes the focus a little, but the meaning stays basically the same.

Still, in normal usage, the original order sounds the most straightforward: first the advice/command, then the explanation.