प्रापक का पता लिखिए और डाक टिकट चिपकाइए।

This uses the Hindi possessive pattern:

X का/की/के Y = Y of X / X’s Y

So:

प्रापक का पता = the recipient’s address

Here का is used because पता is a masculine singular noun. If the following noun were feminine singular, you would use की; if plural or masculine plural, के.

In Hindi, the subject is often omitted when it is obvious. In a command like this, the understood subject is you.

Because the verb forms are polite—लिखिए and चिपकाइए—the implied you is आप.

So the full sense is:

[आप] प्रापक का पता लिखिए और डाक टिकट चिपकाइए।

But Hindi normally leaves आप unstated here.

लिखिए is a polite imperative form of लिखना (to write). It is used for:

• polite instructions
• respectful requests
• formal directions

So लिखिए means please write or write in a polite/formal way.

Compare:

• लिख — very informal
• लिखो — informal
• लिखिए — polite/formal

Because the verb here is चिपकाना, which means to stick/attach/affix something.

Its polite imperative is चिपकाइए = please stick/affix

By contrast, चिपकिए would come from चिपकना, which is an intransitive verb meaning something like to stick/cling. That would not fit this sentence, because here you are attaching a stamp to something.

So:

• चिपकाना → चिपकाइए = affix it
• चिपकना → चिपकिए = cling/stick yourself

डाक टिकट is the standard Hindi term for a postage stamp.

• डाक = post, mail
• टिकट = ticket

Even though टिकट often means ticket, in this fixed expression डाक टिकट means stamp. It is just the normal word combination used for postal stamps.

Hindi usually follows Subject–Object–Verb order, so the thing being acted on comes before the verb.

That is why you get:

• प्रापक का पता
  • लिखिए
• डाक टिकट
  • चिपकाइए

This is very natural in Hindi instructions. English often places the verb earlier, but Hindi normally keeps the verb toward the end of each clause.

और means and. It connects the two commands:

• प्रापक का पता लिखिए
• डाक टिकट चिपकाइए

So the sentence gives two actions in sequence:

1. write the recipient’s address
2. affix the postage stamp

Yes. It sounds polite and formal, which is exactly what you would expect in instructions on a form, envelope, or postal notice.

The formality comes mainly from the verb endings:

• लिखिए
• चिपकाइए

A less formal version might use:

• लिखो
• चिपकाओ

But the sentence you have is the appropriate style for written directions.

। is the standard Devanagari full stop. It is called the danda.

It functions like an English period:

• English: .
• Hindi/Devanagari: ।

So प्रापक का पता लिखिए और डाक टिकट चिपकाइए। is punctuated normally for Hindi writing.