bimilbeonhoreul hamburo allyeo jumyeon an dwaeyo.

함부로 is an adverb meaning something like:

• carelessly
• recklessly
• without thinking
• indiscriminately
• to just do something freely when you shouldn’t

In this sentence, it means you should not give out your password lightly or to just anyone.

So 함부로 알려 주면 안 돼요 has the feeling of:

• don’t tell it carelessly
• don’t give it out casually
• don’t share it with people without caution

알려 주다 means to tell someone / to let someone know.

Here:

• 알리다 = to inform, notify
• 알려 주다 = to tell someone, to let someone know

The 주다 part often adds the idea that the action is done for another person, so it sounds natural when talking about giving information to someone.

So:

• 비밀번호를 알려요 = I inform/tell the password
• 비밀번호를 알려 줘요 = I tell someone the password / let someone know the password

In everyday Korean, 알려 주다 is very common for telling someone information.

-면 means if or when.

So 알려 주면 literally means:

• if you tell (it)
• if you let someone know

The whole sentence is structured like:

• 비밀번호를 함부로 알려 주면 안 돼요
• If you carelessly tell your password, it is not okay

This is a very common Korean way to express a rule or prohibition.

안 돼요 literally means it doesn’t work / it’s not allowed / it’s not okay.

In practice, it often means:

• you must not
• you shouldn’t
• don’t

So in this sentence, 알려 주면 안 돼요 means:

• you must not tell it
• you shouldn’t give it out

Even though the literal structure is if you tell it, it’s not okay, the natural English meaning is a prohibition.

Korean often leaves out the subject when it is obvious from context.

So this sentence does not say you, but it is understood as something like:

• You must not carelessly share your password
• People should not carelessly share passwords

Depending on the context, it could be directed:

• specifically to you
• generally to anyone

Omitting subjects is extremely common in Korean.

를 is the object marker.

It marks 비밀번호 as the thing being told/shared.

So:

• 비밀번호 = password
• 비밀번호를 = password + object marker

It shows that the password is the object of 알려 주다.

Yes, 비밀번호는 is possible in some contexts, but it would change the nuance.

• 비밀번호를 simply marks password as the object.
• 비밀번호는 adds topic/contrast emphasis, like as for the password...

So:

• 비밀번호를 함부로 알려 주면 안 돼요 = A neutral, standard warning.
• 비밀번호는 함부로 알려 주면 안 돼요 = As for passwords, you must not share them carelessly.

The version with 를 is very natural for a straightforward rule.

Not in this sentence.

Here, 알려 주다 comes from 알리다 + -어 주다.

• 알리다 = to inform
• 알리어 주다 → 알려 주다

So 알려 주다 means to let someone know / to tell someone.

This is easy to confuse with 알다 (to know), but here the meaning is definitely to inform someone, not to know.

Yes, functionally it is.

Grammatically, it looks like a statement:

• if you do X, it is not okay

But in actual use, it works as a warning, rule, or prohibition.

So it is similar to:

• Don’t share your password carelessly.

Korean often expresses commands and rules in this softer, indirect way.

안 돼요 is polite casual style.

It is polite enough for many everyday situations, such as:

• speaking to a customer
• giving a general warning
• talking politely in normal conversation

Other levels include:

• 안 돼 = casual/informal
• 안 돼요 = polite
• 안 됩니다 = more formal/stiffer

So this sentence is polite, but not extremely formal.

Yes.

• 안 돼요 sounds polite and natural in conversation.
• 안 됩니다 sounds more formal, official, or rule-based.

For example:

• 비밀번호를 함부로 알려 주면 안 돼요 = polite warning
• 비밀번호를 함부로 알려 주면 안 됩니다 = more formal instruction, like in a notice or workplace policy

Both are correct. The difference is mainly tone and formality.

Yes. 함부로 is a common adverb used with many actions when someone does something without proper care or permission.

Examples:

• 함부로 만지지 마세요 = Don’t touch it carelessly.
• 함부로 말하지 마세요 = Don’t speak carelessly.
• 함부로 들어오면 안 돼요 = You must not come in just like that.

So in this sentence, it naturally modifies the act of sharing the password.

A very literal breakdown is:

• 비밀번호를 = the password
• 함부로 = carelessly / indiscreetly
• 알려 주면 = if you tell someone / if you let someone know
• 안 돼요 = it is not okay

So literally:

• If you carelessly let someone know the password, it is not okay.

Natural English:

• You must not carelessly share your password.
• Don’t give out your password carelessly.