Bir gün seninle sahilde yürümek istiyorum.

Here bir gün means one day / someday, not literally for one day.

In Turkish, bir can mean:

• one
• a / an

But in the expression bir gün, it very often means one day, someday.

So in this sentence, Bir gün seninle sahilde yürümek istiyorum means something like:

• I want to walk on the beach with you someday
• One day, I want to walk on the beach with you

If you wanted to say for one day in a more literal time-length sense, Turkish would usually be expressed differently.

Seninle means with you.

It is made of:

• senin = your / of you
• -le = with

So:

• benimle = with me
• seninle = with you
• onunla = with him/her/it
• bizimle = with us

In modern Turkish, ile means with, and it is often attached to the previous word as -le / -la.

So these are equivalent:

• senin ile
• seninle

The attached form seninle is much more natural in everyday Turkish.

Because the standard form is built from the pronoun’s oblique/genitive-style form:

• benimle
• seninle

So seninle is the normal standard Turkish form for with you.

You may hear senle in speech, and it is common in informal spoken Turkish, but seninle is the safer form for learners and the one you should usually write.

Sahilde means on the beach or at the beach.

It is made of:

• sahil = beach / shore / coast
• -de = in / at / on

So:

• evde = at home
• okulda = at school
• masada = on the table
• sahilde = on/at the beach

The ending -de / -da / -te / -ta is the locative case, used to show location.

Here, sahilde yürümek means to walk on the beach.

This is because of vowel harmony.

The locative ending changes depending on the last vowel of the word:

• -de / -da
• and after some consonants, -te / -ta

Since sahil has i as its last vowel, the correct form is -de:

• sahil + de = sahilde

Compare:

• parkta = in the park
• evde = at home
• okulda = at school

So the form changes automatically to match Turkish sound patterns.

Because after istemek (to want), Turkish usually uses the infinitive form of the other verb.

So the structure is:

[verb in infinitive] + istiyorum
= I want to ...

Examples:

• gitmek istiyorum = I want to go
• uyumak istiyorum = I want to sleep
• konuşmak istiyorum = I want to speak
• yürümek istiyorum = I want to walk

So:

• yürümek = to walk
• istiyorum = I want

Together:

• yürümek istiyorum = I want to walk

İstiyorum means I want.

It comes from:

• istemek = to want
• istiyor- = present continuous/present stem
• -um = I

So:

• istiyorum = I want
• literally, Turkish uses the present continuous form here

This is very normal in Turkish. The form that looks like I am wanting in English is simply the standard way to say I want in Turkish.

Other examples:

• biliyorum = I know
• seviyorum = I love / like
• anlıyorum = I understand

Yes, Turkish word order is flexible, although some orders sound more neutral than others.

This sentence:

• Bir gün seninle sahilde yürümek istiyorum

is natural and clear.

A more literal breakdown is:

• Bir gün = one day
• seninle = with you
• sahilde = on the beach
• yürümek = to walk
• istiyorum = I want

Turkish often puts the main conjugated verb at the end, so istiyorum comes last.

You could also say:

• Seninle bir gün sahilde yürümek istiyorum
• Bir gün sahilde seninle yürümek istiyorum

These are also understandable, but they may shift emphasis slightly. Turkish often moves parts around for focus, while keeping the verb near the end.

Yes, in this context it is a very natural equivalent.

Literally, sahilde means at/on the beach, and yürümek means to walk. So:

• sahilde yürümek = to walk on the beach

Depending on context, English might say:

• walk on the beach
• walk along the beach
• take a walk by the beach

But sahilde yürümek is a normal and simple Turkish way to express the idea.

Yes, it can sound romantic, depending on context.

Bir gün seninle sahilde yürümek istiyorum has a soft, warm feeling because:

• bir gün suggests a hope or dream
• seninle makes it personal
• sahilde yürümek is often associated with romance

So it could sound like:

• a romantic wish
• a sweet future idea
• a gentle personal statement

Of course, tone and situation matter. It could also simply be affectionate or friendly, but many learners will hear it as slightly romantic.

You can understand it word-for-word, but a natural English translation should be smoother.

Word-for-word:

• Bir gün = one day
• seninle = with you
• sahilde = on/at the beach
• yürümek = to walk
• istiyorum = I want

A natural English translation would be:

• I want to walk on the beach with you one day
• One day, I want to walk on the beach with you

So the Turkish sentence does not need to match English word order exactly. Understanding the parts is useful, but translating naturally is better than translating mechanically.