Kulaklık ve ekran koruyucuyu bir arada kullanmak bazen pratik olur.

In Turkish only definite (i.e. specific) direct objects get the accusative -(y)I suffix.

• kulaklık here is general (“headphones” in the abstract), so it stays unmarked.
• ekran koruyucu refers to a particular screen protector (the one you own), so it becomes ekran koruyucuyu with -(y)I.

You could also mark both objects for emphasis:
“Kulaklığı ve ekran koruyucuyu bir arada kullanmak bazen pratik olur.”

When two nouns are coordinated with ve, Turkish lets you put the accusative suffix on only the second noun and it covers both:

• Elma ve armudu yedim. (I ate the apple and the pear.)

Alternatively, you may attach -(y)I to both nouns if you want extra clarity or emphasis:

• Elmayı ve armudu yedim.

Turkish needs a buffer consonant y when attaching -(y)I to a word that ends in a vowel:

ekran koruyucu + y + u → ekran koruyucuyu

Here:

• ekran koruyucu ends in -u,
• -(y)I takes the y buffer and the vowel harmonizes to u (back, rounded).

Both mean “together,” but there’s a slight nuance:

• bir arada literally “in one place/setting,” emphasizing side-by-side use.
• birlikte is more general “together” or “at the same time.”

In your sentence you could swap them without much change:

• Kulaklık ve ekran koruyucuyu birlikte kullanmak bazen pratik olur.

In Turkish an infinitive (verb+mak/mek) can act like a noun. The structure [X yapmak] + (adverb) + olur means “doing X becomes…” or “it is (adjective) to do X.”

So:

• Kulaklık ve ekran koruyucuyu bir arada kullanmak = “Using headphones and a screen protector together”
• It functions as the subject of bazen pratik olur.

The verb olmak (“to be/become”) in the simple present tense olur expresses general truths or habitual observations:

• pratik olur = “it is/ turns out practical” (in general or from time to time)
• pratik oluyor would suggest “it is becoming practical right now” (ongoing)
• pratik oldu would state a completed event: “it became practical (once).”

All three can translate as “convenient/easy/useful,” but:

• kolay = easy (low effort)
• kullanışlı = useful, handy (serves a purpose well)
• pratik = practical, often emphasizing efficiency or convenience in real-world use

Here pratik highlights that combining both items in one setup makes everyday life smoother.

In Turkish, many items that come in pairs (glasses, shoes, headphones) use a singular noun:

• kulaklık covers the concept “a pair of headphones”
• gözlük covers “a pair of glasses”

If you pluralize (kulaklıklar), you’d imply “multiple distinct headphone sets.”

Yes, adverbs are fairly flexible in Turkish. You can say either:

• Bazen kulaklık ve ekran koruyucuyu bir arada kullanmak pratik olur.
• Kulaklık ve ekran koruyucuyu bir arada kullanmak bazen pratik olur.

The emphasis might shift slightly, but both are correct.

ekran koruyucu is a compound noun written as two separate words:

• ekran (screen) + koruyucu (protector)

No hyphen is required. Many Turkish compounds follow the same pattern:

• cep telefonu (cell phone)
• çamaşır makinesi (washing machine)