Ben sana bir şey söylemek istiyorum.

Yes. Turkish often drops subject pronouns because the verb already shows the person.

• istiyorum already means I want
• So Sana bir şey söylemek istiyorum is completely natural

Keeping ben adds emphasis, contrast, or extra clarity, like I want to tell you something.

Because sana is the form that means to you.

• sen = you (basic form)
• sana = to you
• seni = you as a direct object

With söylemek, the person receiving the words is usually marked like to someone, so sana is the right choice here.

Yes. This is the dative case, which often gives the meaning to or toward.

With regular nouns, you add -a / -e:

• okul → okula = to school
• ev → eve = to the house

Personal pronouns are a bit irregular:

• ben → bana
• sen → sana

So you should learn bana and sana as special forms.

Literally, bir şey means one thing, but in everyday Turkish it often means something.

It is written as two words in standard Turkish:

• bir = one / a
• şey = thing

So:

• bir şey = something
• not standard: birşey

Because Turkish uses the infinitive ending -mek / -mak instead of a separate word like English to.

• söylemek = to say / to tell
• yapmak = to do / to make
• gitmek = to go

So söylemek istiyorum literally works like I want to say/tell.

Söylemek is the infinitive, or dictionary form, of the verb.

It is made of:

• söyle- = the verb stem
• -mek = the infinitive ending

So söylemek means to say or to tell, depending on context.

In this sentence, because there is a receiver (sana), English often translates it as tell.

Turkish usually puts tense and person endings directly onto the verb.

istiyorum breaks down like this:

• iste- = want
• -iyor = present continuous / present-time marker
• -um = I

So istiyorum means I want or more literally I am wanting.

A small sound change happens:

• iste- + -iyor becomes istiyor-
• then -um is added: istiyorum

Yes, it is, but in Turkish the -iyor form is very commonly used for what English would simply call the present.

So istiyorum naturally means:

• I want
• not only I am wanting

This is very normal with many everyday verbs.

Turkish usually prefers a verb-final structure, so the main verb or predicate tends to come at the end.

This sentence is arranged like:

• Ben = subject
• sana = indirect object
• bir şey = object
• söylemek istiyorum = verbal idea + main predicate

So the sentence ends with the main idea istiyorum.

English is more like:

• I want to tell you something

Turkish is more like:

• I to-you something to-tell want

Yes, Turkish word order is flexible, but not all orders sound equally neutral.

Very natural:

• Sana bir şey söylemek istiyorum.
• Ben sana bir şey söylemek istiyorum.

Possible with emphasis:

• Bir şey sana söylemek istiyorum.
  This can emphasize bir şey

Less natural in ordinary speech:

• İstiyorum sana bir şey söylemek.

As a learner, the safest neutral pattern is:

• (Ben) sana bir şey söylemek istiyorum.

Because it is indefinite.

In Turkish, indefinite direct objects are often left unmarked:

• bir şey söylemek = to say/tell something

But definite or specific objects often take the accusative:

• o şeyi söylemek = to say/tell that thing

So here bir şey is general and indefinite, which is why it appears without -i.

It can correspond to either one in English.

• If the focus is just on words being spoken, English may use say
• If there is a listener or recipient, English often uses tell

In this sentence, because of sana (to you), the most natural English translation is usually tell you something.

Sometimes, yes, but söylemek is more natural here.

Both verbs can relate to speaking, but they are not always interchangeable.

• söylemek often means to say / tell
• demek often means to say, but also to mean

For I want to tell you something, söylemek is the safer and more natural choice.

Change sana to size if you are speaking formally to one person or to more than one person.

• Sana bir şey söylemek istiyorum. = informal singular
• Size bir şey söylemek istiyorum. = formal singular or plural

So the level of politeness depends mainly on sana / size here.

A rough guide is:

• bir ≈ beer
• şey ≈ shey

The letter ş is pronounced like English sh.

So bir şey sounds roughly like beer shey.

A rough approximation is söy-le-mek.

A few useful points:

• ö does not have an exact English equivalent
• y sounds like English y
• ş in Turkish always sounds like sh, but there is no ş in söylemek

So try to say it in three parts:

• söy
• le
• mek

Even if your ö is not perfect at first, people will usually still understand you from context.