Il y a un drôle de bruit dans le couloir.

Here, il y a means there is.

So:

• Il y a un drôle de bruit = There is a strange/funny noise

More generally, il y a is the standard French expression for saying that something exists or is present somewhere.

Examples:

• Il y a un chat dehors. = There is a cat outside.
• Il y a des enfants dans le jardin. = There are children in the garden.

It is best learned as a fixed expression.

The il in il y a does not refer to a person or thing here. It is just part of the expression.

English does something similar with there in there is. That there does not really mean a place in the normal sense; it helps form the structure. In French, il y a works the same way as a whole chunk.

So you should not try to translate each word too literally every time. Just recognize:

• il y a = there is / there are

Yes. Il y a is used for both singular and plural.

• Il y a un bruit. = There is a noise.
• Il y a des bruits. = There are noises.

English changes between is and are, but French keeps il y a the same.

In this sentence, drôle means strange, odd, or funny-looking/sounding in the sense of unusual.

So un drôle de bruit usually means:

• a strange noise
• an odd noise
• a funny noise

Important: drôle can also mean funny in the sense of amusing.

For example:

• C’est drôle. = That’s funny.

So the exact meaning depends on context. With bruit, it usually suggests something unusual or suspicious rather than something hilarious.

Because drôle de + noun is a very common French pattern.

• un drôle de bruit
• un drôle de type
• une drôle d’idée

This structure means something like a strange/odd/funny ...

If you say un bruit drôle, it sounds unnatural in most contexts. French normally uses drôle de before the noun for this idea.

So this is not just a normal adjective placement issue. It is really a set pattern:

• drôle de + noun = odd/strange/funny-looking or sounding noun

The de is part of the expression drôle de + noun.

It does not translate neatly word for word into English. You should think of the whole chunk together:

• un drôle de bruit = a strange noise

Not:

• a funny of noise

So in practice, just learn:

• drôle de
  • noun

A few more examples:

• un drôle de nom = a strange name
• une drôle de sensation = a strange feeling

If the noun is plural, you still keep the pattern:

• de drôles de bruits = strange noises

Because bruit is a masculine noun.

• un bruit = a noise

So the article must be masculine singular too:

• un drôle de bruit

If the noun were feminine, you would use une:

• une drôle d’histoire = a strange story

That happens because of elision.

When de comes before a word beginning with a vowel sound, it usually shortens to d’:

• de histoire becomes d’histoire

So:

• un drôle de bruit — no elision, because bruit starts with a consonant sound
• une drôle d’idée — elision, because idée starts with a vowel sound

Dans le couloir means in the hallway or in the corridor.

• dans = in / inside
• le couloir = the hallway, corridor

It is used because the noise is located in that space.

So the sentence structure is:

• Il y a = there is
• un drôle de bruit = a strange noise
• dans le couloir = in the hallway

Together: There is a strange noise in the hallway.

Here, le couloir refers to the hallway as a specific place, probably one that is already understood from the situation.

• dans le couloir = in the hallway

If you said dans un couloir, that would mean in a hallway, with a less specific meaning.

Du couloir would not fit here, because du usually means of the or some depending on context, and that is not the idea in this sentence.

Use il y a when you are introducing the existence or presence of something.

• Il y a un drôle de bruit dans le couloir. = There is a strange noise in the hallway.

Use c’est more to identify or comment on something already pointed out or known.

• C’est un drôle de bruit. = That is a strange noise.

So in your sentence, the speaker is announcing that such a noise exists, which is why il y a is the natural choice.

A rough English-style guide would be:

eel ya uhn drohl duh brwee dahn luh koo-lwar

A few useful points:

• Il y a is often said very smoothly, almost like eel-ya
• the final t in bruit is silent
• couloir sounds roughly like koo-lwar
• un has a nasal vowel, so it is not exactly like English uhn, but that approximation helps at first

If you want an IPA version, it is approximately:

il j‿a œ̃ dʁɔl də bʁɥi dɑ̃ lə kulwaʁ

It is completely natural and neutral. You could say it in everyday conversation without sounding especially formal or especially casual.

For example, if you hear something at home, at school, or at work, Il y a un drôle de bruit dans le couloir sounds very normal.