bimilbeonhoreul dasi hwaginhae jwo.

비밀번호 means password.
를 is the object particle (을/를) marking 비밀번호 as the thing being checked/confirmed.

• 비밀번호를 다시 확인해 줘. = (Please) check the password again.
  If the noun ended in a consonant, you’d use 을 instead (e.g., 코드를 vs 값을).

다시 means again. It commonly goes before the verb phrase it modifies:

• 비밀번호를 다시 확인해 줘.
  You can also place it earlier for emphasis/flow:
• 다시 비밀번호를 확인해 줘.
  Both are natural; the original is probably the most neutral.

Yes. 확인하다 is the dictionary form meaning to check / to confirm / to verify.
It’s a 하다-verb, so it conjugates like this:

• 확인하다 → 확인해 (informal) / 확인해요 (polite) / 확인합니다 (formal)

-아/어 주다 (here: 해 줘) adds the meaning of doing something as a favor / for someone.
So:

• 비밀번호를 다시 확인해. = Check it again. (more direct)
• 비밀번호를 다시 확인해 줘. = Check it again for me, please. (softer/more request-like)

줘 is the informal intimate style (반말), used with close friends, younger people, kids, etc.
More polite options:

• 비밀번호를 다시 확인해 줘요. (polite but still conversational)
• 비밀번호를 다시 확인해 주세요. (polite request; very common)
• 비밀번호를 다시 확인해 주실래요? (even softer/polite)
• 비밀번호를 다시 확인해 주십시오. (very formal)

Common natural pronunciations:

• 확인해 is often pronounced closer to 화긴해 (확인 [화긴]) in fast speech.
• Whole sentence (approx.): 비밀번호를 다시 화긴해 줘.
  Also, 줘 is a contraction of 주어 (historically), and it’s pronounced simply 줘.

Korean frequently omits subjects when they’re obvious from context.
Here, the implied meaning is:

• (You,) check the password again (for me).
  No explicit 너/당신 is needed and often sounds unnatural unless emphasizing.

As written (…해 줘), it feels like you’re talking to a person in an informal way.
For UI/system messages, Korean typically uses more neutral/polite phrasing, such as:

• 비밀번호를 다시 확인해 주세요.
• 비밀번호를 다시 확인하세요.
• 비밀번호를 다시 입력해 주세요. (if you mean “re-enter”)

It can cover both, depending on context:

• If you’re making sure it’s correct: check / verify
• If you’re agreeing it’s correct or final: confirm
  With 비밀번호, it usually means verify/check (again)—often like “double-check it” or “make sure the password is correct,” and sometimes it implies re-checking what was typed.