अपॉइंटमेंट के दौरान पालतू जानवर शांत है।

के दौरान means during. In Hindi, this is a very common fixed expression for talking about something happening in the course of an event or period of time.

So:

• अपॉइंटमेंट के दौरान = during the appointment

It is best learned as a chunk.

Hindi uses postpositions rather than English-style prepositions. That means the relational word usually comes after the noun phrase, not before it.

So English:

• during the appointment

Hindi:

• अपॉइंटमेंट के दौरान

Literally, it feels more like:

• appointment + during

That is normal Hindi structure.

In के दौरान, the के is part of the full expression. You should usually treat के दौरान as one grammatical unit meaning during.

The noun before it goes into the form used before postpositions. With अपॉइंटमेंट, the form does not visibly change, so you just see:

• अपॉइंटमेंट के दौरान

Even though के often means something like of or is used in possessive patterns, here it is simply part of the set phrase के दौरान.

It is an English loanword written in Devanagari. Hindi very often uses borrowed English words, especially for modern situations, offices, medical settings, scheduling, and daily conversation.

So अपॉइंटमेंट is completely natural in many contexts.

Depending on context, a more traditional Hindi word might sometimes be used, but अपॉइंटमेंट is very common and easy to understand.

Literally:

• पालतू = domesticated / kept as a pet
• जानवर = animal

So पालतू जानवर literally means pet animal, which in natural English is just pet.

You may also hear this phrase used in a broad way for any domesticated animal kept by a person.

Because पालतू जानवर is being treated as singular here.

So:

• पालतू जानवर शांत है। = The pet is calm/quiet.

If it were plural, you would use:

• पालतू जानवर शांत हैं। = The pets are calm/quiet.

A useful detail: जानवर often looks the same in singular and plural in the direct form, so the verb helps show whether the meaning is singular or plural.

शांत is an indeclinable adjective in this kind of use, so it usually stays the same regardless of gender or number.

That means you can say:

• कुत्ता शांत है।
• बिल्ली शांत है।
• जानवर शांत है।
• जानवर शांत हैं।

In all of these, शांत stays शांत.

This is different from adjectives like अच्छा, which do change:

• अच्छा
• अच्छी
• अच्छे

It can suggest either, depending on context. In this sentence, शांत most naturally means calm or well-behaved/quiet during the appointment.

For a pet, शांत often suggests:

• not agitated
• not causing trouble
• calm and settled

So it is broader than just not making noise.

Hindi does not normally use articles like a, an, and the the way English does.

So:

• पालतू जानवर can mean a pet, the pet, or pet animals, depending on context.

In this sentence, the context tells you it means the pet or the pet animal.

No. The sentence you have is natural, but Hindi word order is somewhat flexible.

The given sentence:

• अपॉइंटमेंट के दौरान पालतू जानवर शांत है।

A very natural alternative is:

• पालतू जानवर अपॉइंटमेंट के दौरान शांत है।

Both mean the same thing. The original version puts the time phrase first, which gives a slight emphasis to during the appointment.

Sometimes, but it changes the nuance.

• शांत = calm, peaceful, quiet in behavior
• चुप = silent, not speaking, not making noise

For a pet during an appointment, शांत is better because it suggests the animal is calm overall, not just silent. चुप would sound narrower and less natural in many situations.