Eve gelince anahtarı masaya bırakıyorum.

Because eve means to home / homeward, while evde means at home.

• ev + -e → eve = motion toward home
• ev + -de → evde = location at home

With gelmek (to come), Turkish normally uses the destination, so eve gelmek means to come home.

Gelince means when (someone) comes, once (someone) comes, or sometimes as soon as (someone) comes, depending on context.

It is built from:

• gel- = come
• -ince = a suffix meaning when / once

So eve gelince means when I come home or when I get home in this sentence.

Because Turkish often expresses ideas like when, after, or while with suffixes instead of separate words.

Here, the idea of when is contained inside gelince. English uses a separate word, but Turkish often attaches that meaning directly to the verb.

So instead of something like when come, Turkish says gelince.

By itself, gelince does not show person clearly. The subject is understood from context.

In this sentence, the main verb is bırakıyorum, which means I leave / I am leaving, so the natural interpretation is:

• Eve gelince = when I come home
• bırakıyorum = I leave

So both parts are understood as having the same subject: I.

The -ı is the definite accusative ending. It marks anahtarı as a specific direct object: the key.

• anahtar = a key / key
• anahtarı = the key (specific one, as the object of the verb)

Turkish often marks definite direct objects this way. So:

• anahtar bırakıyorum = I leave a key / I leave keys
• anahtarı bırakıyorum = I leave the key

Because masaya shows movement or placement toward the table, while masada means on/at the table as a fixed location.

• masa + -ya → masaya = to the table / onto the table
• masa + -da → masada = on the table / at the table

With a verb like bırakmak (to leave / put down), Turkish often uses the dative because the object is being placed somewhere.

So masaya bırakmak literally feels like put/leave onto the table, even if natural English says leave it on the table.

That y is a buffer consonant.

When a Turkish word ends in a vowel and the suffix also begins with a vowel, Turkish often inserts y to make pronunciation easier.

• masa + a would be awkward
• so it becomes masa + y + a → masaya

This happens very often in Turkish.

Bırakıyorum is the present continuous form, but in Turkish this form is used more broadly than English I am leaving.

It can mean:

• something happening now
• something habitual
• something done in a regular situation
• sometimes a planned or expected action

So in this sentence, bırakıyorum can naturally be translated as I leave the key on the table when I come home.

By contrast, bırakırım often sounds more like:

• I usually leave
• I would leave
• I do leave

Both can be possible in the right context, but bırakıyorum is very natural here.

Turkish usually leaves subject pronouns out when the verb already shows who the subject is.

In bırakıyorum, the ending -yorum tells you the subject is I.

So ben is not necessary. Turkish prefers to omit it unless you want emphasis:

• Ben bırakıyorum = I am the one leaving it
• Bırakıyorum = simply I leave / I am leaving

A very literal breakdown is:

• Eve = home / to home
• gelince = when I come
• anahtarı = the key
• masaya = onto the table
• bırakıyorum = I leave

So the overall structure is:

When I come home, I leave the key on the table.

Turkish often puts:

1. the time or condition part first
2. the main verb at the end

That is why bırakıyorum comes last.

It can mean either in different contexts, but here it is best understood as home.

In expressions like eve gitmek and eve gelmek, Turkish commonly uses ev in the sense of home:

• eve gitmek = to go home
• eve gelmek = to come home

So although ev literally means house/home, the natural English meaning here is home.