जो तोहफ़ा तुम चुनोगी, वह मैं लपेटूँगी।

This is a very common Hindi pattern called the relative-correlative construction.

• जो = which / that / whichever
• वह = that / that one

So:

• जो तोहफ़ा तुम चुनोगी, वह मैं लपेटूँगी। = The gift that you choose, I will wrap = more naturally, Whichever gift you choose, I’ll wrap it

Hindi often pairs these two words:

• जो ... वह ...
• जिस ... उस ...
• जहाँ ... वहाँ ...
• जब ... तब ...

So the sentence is built as:

• जो तोहफ़ा तुम चुनोगी = the gift that/whichever gift you choose
• वह मैं लपेटूँगी = that, I will wrap

Because चुनोगी agrees with tum here, and the person being addressed is female.

With tum in the future tense:

• तुम चुनोगे = you will choose (to a male / masculine)
• तुम चुनोगी = you will choose (to a female / feminine)

So this sentence is being said to a woman or girl.

Because it agrees with the speaker, मैं.

In the future tense, Hindi verbs often show the gender of the subject:

• मैं लपेटूँगा = I will wrap (male speaker)
• मैं लपेटूँगी = I will wrap (female speaker)

So this sentence is spoken by a female speaker.

तोहफ़ा means gift or present.

It is a masculine noun, which is why its basic singular form ends in -ा:

• एक तोहफ़ा = a gift
• अच्छा तोहफ़ा = a good gift

In this sentence, though, the verb forms are not agreeing with तोहफ़ा. They are agreeing with the people involved:

• चुनोगी agrees with tum
• लपेटूँगी agrees with main

Because choose in Hindi often takes a direct object without को.

So:

• तुम तोहफ़ा चुनोगी = you will choose a gift

This is normal.

You may sometimes see को with direct objects in Hindi, especially when the object is specific, animate, or needs emphasis, but with a thing like तोहफ़ा, leaving out को is completely natural.

Yes. That is also natural.

Hindi allows some flexibility in word order, especially when the grammar is clear.

These are both fine:

• जो toहफ़ा तुम चुनोगी, वह मैं लपेटूँगी।
• तुम जो तोहफ़ा चुनोगी, वह मैं लपेटूँगी।

The first version puts slightly more focus on whichever gift right away.

They mean the same thing here.

• वह is the standard written form
• वो is the very common spoken form

So in speech, many people would say:

• जो तोहफ़ा तुम चुनोगी, वो मैं लपेटूँगी।

But in careful writing, वह is usually preferred.

It can suggest both, but in natural English the best translation is often:

• Whichever gift you choose, I’ll wrap it

The जो ... वह pattern often has this broad meaning of whatever/whichever ... that ... depending on context.

So it is not just identifying one gift; it can also carry the sense of no matter which gift you pick.

Because Hindi usually follows Subject–Object–Verb order, and the verb often comes at the end.

So in the second clause:

• वह = that / it
• मैं = I
• लपेटूँगी = will wrap

Literally, it is something like:

• That, I will wrap

This is normal Hindi structure.

It is correct, and it literally means I will wrap.

But in everyday conversation, many speakers might also say:

• पैक करूँगी = I will pack/wrap
• गिफ्ट रैप करूँगी = I will gift-wrap

So लपेटूँगी is a good Hindi verb, but depending on context, some speakers may prefer a more colloquial expression.

Their dictionary forms are:

• चुनना = to choose
• लपेटना = to wrap

The future forms here are built from those verbs:

• चुनना → चुनोगी
• लपेटना → लपेटूँगी

So the sentence uses two future-tense verbs:

• तुम चुनोगी = you will choose
• मैं लपेटूँगी = I will wrap

The form लपेटूँगी contains ऊँ, which gives a nasalized vowel sound.

This happens in many मैं future forms:

• मैं करूँगी
• मैं जाऊँगी
• मैं लपेटूँगी

That nasalization is part of the normal conjugation. It is not optional in careful pronunciation.

Only the first-person future verb would change:

• जो तोहफ़ा तुम चुनोगी, वह मैं लपेटूँगा।

That means:

• Whichever gift you choose, I will wrap it
  spoken by a male speaker to a female addressee.

And if both the addressee and speaker were male:

• जो तोहफ़ा तुम चुनोगे, वह मैं लपेटूँगा।

So the endings tell you about gender:

• -गी = feminine
• -गा / -गे = masculine forms depending on person/number/politeness context