कितने बजे मिलेंगे? हम बाद में तय करेंगे।

It is the standard way to ask for a clock time: at what time?

So कितने बजे मिलेंगे? means What time shall we meet?

A useful contrast:

• कब मिलेंगे? = When shall we meet? (more general)
• कितने बजे मिलेंगे? = What time shall we meet? (specifically asking for the hour/time)

Because कितने बजे is a fixed Hindi time expression.

Hindi says:

• एक बजे = at one o’clock
• दो बजे = at two o’clock
• तीन बजे = at three o’clock

So the natural question form is कितने बजे?

For a learner, it is best to memorize कितने बजे as one set phrase meaning what time.

Hindi often drops the subject pronoun when it is already clear from context.

So instead of saying:

• हम कितने बजे मिलेंगे?

speakers often just say:

• कितने बजे मिलेंगे?

The second sentence, हम बाद में तय करेंगे, confirms that the meaning is we.

मिलेंगे is the future form of मिलना, which means to meet.

Here it means will meet or, more naturally in English, shall we meet.

So:

• मिलना = to meet
• मिलेंगे = will meet

Because the subject is understood as हम, the sentence means When/what time will we meet?

Yes. By itself, मिलेंगे can also be used with आप or वे, depending on context.

For example:

• हम मिलेंगे = we will meet
• आप मिलेंगे = you will meet (formal/plural)
• वे मिलेंगे = they will meet

So the form alone does not always tell you the subject. In this example, the next sentence makes it clear that we is intended.

Not necessarily. Hindi often leaves that unstated if it is obvious.

In this sentence, मिलेंगे means meet each other or simply meet, so no extra object is needed.

If you want to say whom you will meet, Hindi usually uses से:

• मैं उससे मिलूँगा = I will meet him/her
• हम उनसे मिलेंगे = we will meet them / we will meet you (formal)

But in कितने बजे मिलेंगे?, the meeting is already understood.

Word by word:

• हम = we
• बाद में = later / afterwards
• तय करेंगे = will decide / will fix / will finalize

So the whole sentence means We’ll decide later.

A more literal sense is We will fix it later or We will settle it later.

It comes from तय करना, which means to decide, to fix, or to finalize.

This is a very common Hindi pattern: a noun/adjective-like word plus करना.

Examples:

• तय करना = to decide/fix
• साफ करना = to clean
• शुरू करना = to begin

In तय करेंगे, the word तय stays the same, and करेंगे carries the future meaning.

Because it is understood from the first sentence.

After कितने बजे मिलेंगे?, the listener already knows that the topic is the time of the meeting. So Hindi naturally says just:

• हम बाद में तय करेंगे।

English does the same:

• We’ll decide later.

You do not need to repeat the time.

Yes, in standard Hindi they can.

For a masculine or mixed-gender group:

• हम मिलेंगे
• हम तय करेंगे

For an all-female group:

• हम मिलेंगी
• हम तय करेंगी

So if the speakers are all female, standard Hindi would normally use मिलेंगी and करेंगी.

Yes. A few natural alternatives are:

• कब मिलेंगे? बाद में तय करेंगे।
  = When shall we meet? We’ll decide later.

• कितने बजे मिलना है? बाद में तय करेंगे।
  = What time are we supposed to meet? We’ll decide later.

• हम बाद in तय कर लेंगे।
  = We’ll decide/fix it later.

That last one, तय कर लेंगे, is especially common in everyday speech and has a nice we’ll sort it out later feeling.