जब डेबिट कार्ड गुम हो, तब बैंक शाखा जाइए।

जब ... तब ... is the Hindi correlative pair meaning when ... then ....

So:

• जब = when
• तब = then / at that time

In this sentence, जब डेबिट कार्ड गुम हो, तब बैंक शाखा जाइए literally means something like:

When the debit card is lost, then go to the bank branch.

In natural English, we often just say If your debit card is lost, go to the bank branch, but Hindi often uses जब ... तब ... to link the condition and result.

गुम means lost or missing.

With हो, it forms the idea to be lost / to become missing:

• गुम होना = to be lost, to go missing

So डेबिट कार्ड गुम हो means the debit card is lost or the debit card goes missing.

This is a common Hindi pattern:

• adjective/state word + होना

For example:

• बीमार होना = to become sick / to be sick
• खराब होना = to become bad / to be damaged
• गुम होना = to be lost / go missing

Here हो is being used in a conditional/subjunctive-style clause after जब.

Compare:

• गुम है = is lost (simple statement)
• गुम हो गया है = has gotten lost / has been lost
• गुम ho = be lost / should be lost / if it is lost in a conditional-type structure

In instructions, Hindi often uses this shorter form:

• जब X हो, तब Y कीजिए
• अगर X हो, तो Y कीजिए

So जब डेबिट कार्ड गुम हो means when/if the debit card is lost.

It sounds like an instruction or rule, not just a plain description.

जाइए is a polite imperative form of जाना (to go).

So:

• जा = go (very informal/commanding)
• जाओ = go (informal)
• जाइए = go (polite/respectful)
• जाएँ can also be used in polite/subjunctive contexts

In instructions to customers, the polite form is normal. So बैंक शाखा जाइए means:

Please go to the bank branch.

Even if English translations do not always include please, the Hindi form is polite.

शाखा means branch, especially a branch office of a bank or company.

So:

• बैंक = bank
• शाखा = branch
• बैंक शाखा = bank branch

This means the physical branch office, not banking in general.

So the sentence is specifically telling the person to go to a branch location.

Hindi often leaves out words that are understood from context.

So even though the sentence says:

जब डेबिट कार्ड गुम हो...

the intended meaning is understood as:

when your debit card is lost...

This is very common in instructions, notices, and formal writing. Hindi does not always need to state your if the context already makes it obvious.

A fuller version could be:

• जब आपका डेबिट कार्ड गुम हो, तब बैंक शाखा जाइए।

That is also correct, but the shorter version is natural in formal instructions.

Yes. The subject is implied.

Because the verb is जाइए, the sentence is addressing you politely. So the understood meaning is:

When your debit card is lost, you should go to the bank branch.

Hindi often omits pronouns when the verb ending already makes the meaning clear.

So आप is not written, but it is understood from जाइए.

Yes. A very similar version would be:

अगर डेबिट कार्ड गुम हो, तो बैंक शाखा जाइए।

This also means:

If the debit card is lost, go to the bank branch.

Difference in feel:

• अगर ... तो ... = more directly if ... then ...
• जब ... तब ... = literally when ... then ..., but in instructions it can function similarly

In many practical contexts like notices or instructions, both can work.

No. Another very common expression is based on खोना / खो जाना.

For example:

• डेबिट कार्ड खो जाए = the debit card gets lost
• डेबिट कार्ड खो गया हो = the debit card has been lost

Compared with गुम होना:

• गुम होना often emphasizes being missing
• खो जाना often emphasizes getting lost

In many everyday contexts, they are close in meaning. In formal instructions, गुम हो sounds quite natural.

With motion verbs like जाना, Hindi can often use the destination noun directly without adding में or पर.

So:

• घर जाइए = go home
• स्कूल जाइए = go to school
• बैंक शाखा जाइए = go to the bank branch

If you added a postposition, it would usually change the structure or sound less direct. The bare noun as destination is very common with जाना.

The tone is formal, polite, and instructional.

It sounds like something you might see in:

• a bank notice
• a customer service instruction
• a help page
• an official form or leaflet

The polite imperative जाइए and the structured जब ... तब ... pattern make it sound more formal than casual everyday speech.