Koyunlar sakin görünüyor ama kuzu annesinden ayrılınca hemen ona koştu.

In Turkish, non-human plural subjects very often take a singular verb.

So:

• Koyunlar sakin görünüyor = The sheep look calm

This is completely normal Turkish. You may also sometimes hear plural agreement, but with animals and things, the singular verb is the usual choice.

A useful contrast:

• Çocuklar geliyorlar or Çocuklar geliyor = The children are coming
  plural marking is more likely with people
• Kuşlar uçuyor = The birds are flying
  singular verb is very natural

So in this sentence, görünüyor is not a mistake at all.

Here görünüyor means looks / appears / seems.

It comes from görünmek, which means:

• to appear
• to be visible
• to look / seem

So:

• sakin görünüyor = looks calm / appears calm

Form breakdown:

• görün- = appear, be seen
• -üyor = present continuous

So literally it is something like is appearing, but in natural English here it is best translated as looks or seems.

Turkish has no articles like English the or a/an.

That means nouns often appear by themselves:

• koyunlar = sheep / the sheep
• kuzu = a lamb / the lamb
• anne = mother / the mother

Which English article you use depends on context.

In this sentence, the context makes it natural to translate:

• koyunlar as the sheep
• kuzu as the lamb

So the definiteness is understood without a separate word.

Because kuzu is the subject of the second clause, not the direct object.

Compare:

• Kuzu annesinden ayrılınca... = When the lamb was separated from its mother...
  Here kuzu is doing/undergoing the action as the subject.
• Kuzuyu gördüm = I saw the lamb
  Here kuzuyu is a definite direct object, so it takes the accusative ending -yu.

So in your sentence, plain kuzu is correct.

Annesinden means from his/her/its mother or from the mother of it/him/her.

It breaks down like this:

• anne = mother
• anne-si = his/her/its mother
• anne-si-n-den = from his/her/its mother

So:

• annesinden ayrılınca = when it was separated from its mother

Why the extra parts?

1. -si is the 3rd person possessive ending
   It shows that the mother belongs to someone: its mother
2. -den is the ablative ending, meaning from
3. The -n- is a buffer consonant between the possessive form and the case ending

If you said anneden, it would mean just from a mother or from the mother, but not specifically from its mother.

Ayrılınca means when ... is separated, when ... separates, once ... gets separated, or after ... is separated, depending on context.

It comes from:

• ayrılmak = to separate, to leave, to be separated
• -ınca / -ince = when / once / upon doing

So:

• ayrılınca = when it separated / when it was separated / once it got separated

In this sentence:

• kuzu annesinden ayrılınca = when the lamb got separated from its mother

This suffix is very common in Turkish:

• Gelince haber ver. = Let me know when you come.
• Bitirince ara. = Call me when you finish.

Not exactly in the same way English uses a passive, but it often has a similar meaning.

The verb ayırmak is transitive:

• ayırmak = to separate something

The related verb ayrılmak is intransitive:

• ayrılmak = to separate / to become separated / to leave

So in context:

• kuzu annesinden ayrılınca can be understood as
  when the lamb got separated from its mother

That sounds passive in English, but in Turkish ayrılmak is simply the normal verb you use for be separated / separate from / leave.

Ona means to him / to her / to it.

Here it refers to annesi — the lamb’s mother.

Form breakdown:

• o = he / she / it
• o-na = to him / to her / to it

The -a / -e ending is the dative case, often meaning to or toward.

That fits the verb koşmak:

• birine koşmak = to run to someone
• ona koştu = it ran to her

The -n- is again a buffer consonant, because the pronoun o takes case endings in this special way:

• onu = him/her/it
• ona = to him/her/it
• onda = on him/her/it
• ondan = from him/her/it

Hemen means immediately / right away.

Turkish word order is flexible, and adverbs like hemen can move around depending on emphasis. Here:

• hemen ona koştu = immediately ran to her

Placing hemen before ona koştu gives a natural flow and emphasizes how quickly the lamb reacted.

You could compare:

• Hemen ona koştu.
• Ona hemen koştu.

Both are possible, but the first is a very natural neutral order.

The sentence has two main parts joined by ama (but):

1. Koyunlar sakin görünüyor
   The sheep look calm
2. ama kuzu annesinden ayrılınca hemen ona koştu
   but when the lamb got separated from its mother, it immediately ran to her

A more literal breakdown:

• Koyunlar = sheep
• sakin = calm
• görünüyor = appear/look
• ama = but
• kuzu = lamb
• annesinden = from its mother
• ayrılınca = when it got separated
• hemen = immediately
• ona = to her
• koştu = ran

So the full idea is:

• The sheep look calm, but when the lamb got separated from its mother, it immediately ran to her.

Ama simply means but and marks a contrast.

The contrast is:

• the sheep look calm
• but the lamb reacts quickly when separated

So ama is a very natural choice.

Other connectors exist, such as fakat or ancak, but ama is very common in everyday Turkish and sounds completely natural here.