כשהתינוק בוכה, אחותו נותנת לו צעצוע ומנסה להרגיע אותו.

It is made of three parts:

• כש־ = when
• ה־ = the
• תינוק = baby

So כשהתינוק literally means when the baby.

In Hebrew, short function words like כש־ often attach directly to the next word instead of standing separately.

Hebrew present-tense forms often cover both ideas:

• an action happening now: is crying
• a general/repeated action: cries

So כשהתינוק בוכה can mean either when the baby is crying or when the baby cries, depending on context.

This is very normal in Hebrew. The present form does more work than the English present sometimes does.

Hebrew often shows possession by adding a suffix to the noun.

• אחות = sister
• ־ו = his

So:

• אחותו = his sister
• אחותה = her sister

This is a very common pattern in Hebrew.

Because the subject is אחותו = his sister, and sister is feminine singular.

In Hebrew, present-tense verbs agree with the subject in gender and number. So:

• נותן = masculine singular
• נותנת = feminine singular

Since his sister is doing the action, Hebrew uses the feminine form נותנת.

It actually is feminine here, because its subject is still אחותו.

The tricky part is that in unpointed Hebrew spelling, מנסה can represent both:

• masculine singular
• feminine singular

The difference is clearer in pronunciation and with vowel marks, but not in ordinary spelling. In this sentence, context tells you it is feminine: his sister ... tries.

They are two different kinds of him:

• לו = to him / for him
• אותו = him as a direct object

So in the sentence:

• נותנת לו צעצוע = gives him a toy
• להרגיע אותו = to calm him

English uses him for both, but Hebrew distinguishes them.

Because את is used before a definite direct object, and צעצוע here is indefinite: a toy, not the toy.

So:

• נותנת לו צעצוע = gives him a toy
• but נותנת לו את הצעצוע = gives him the toy

No את is needed with an indefinite noun like צעצוע here.

Because forms like אותו, אותה, אותי, אותך are object pronoun forms built on את.

So אותו already means him as a direct object. You do not add another את before it.

That is why Hebrew says:

• להרגיע אותו

not

• להרגיע את אותו for this meaning

להרגיע is the infinitive, meaning to calm, to soothe, or to calm down someone.

After מנסה = tries, Hebrew normally uses an infinitive:

• מנסה להרגיע = tries to calm

So the structure is very similar to English:

• tries to calm

Because the subject stays the same: his sister.

Hebrew, like English, does not need to repeat the subject if two verbs share it:

• אחותו נותנת לו צעצוע ומנסה להרגיע אותו

That means:

• His sister gives him a toy and tries to calm him

Hebrew could say והיא מנסה if it wanted extra emphasis, but it is not necessary.

This order is very natural in Hebrew:

• verb: נותנת
• indirect object: לו
• direct object: צעצוע

So literally it is something like gives to him a toy, which is a normal Hebrew pattern.

English usually prefers gives him a toy, but Hebrew commonly keeps the recipient pronoun right after the verb.

A rough pronunciation is:

Ksheha-tinok bokhe, achoto notenet lo tsa'atsu'a u-menasa lehargi'a oto.

A few notes:

• kh / ch here is the throat sound in words like Bach
• אותו = oto
• צעצוע is commonly pronounced something like tsa-atsu-a

You do not need perfect transliteration, but this should help you read it aloud.