Η ρεσεψιόν του ξενοδοχείου είναι ανοιχτή όλη νύχτα.

Because ρεσεψιόν is treated as a feminine noun in Greek, so it takes the feminine singular article η.

Even though ρεσεψιόν is a loanword and does not change its ending like many Greek nouns do, its gender still matters:

• η ρεσεψιόν = the reception / front desk

With many indeclinable loanwords, the article is what tells you the gender and case.

Ρεσεψιόν is a common loanword meaning the reception desk, especially in a hotel. It is very commonly used in everyday Greek.

In this sentence, it refers to the hotel’s front desk / reception.

It is usually indeclinable, which means the noun itself normally does not change form. The article around it does the grammatical work.

Του ξενοδοχείου is the genitive singular form, and it means of the hotel.

So:

• το ξενοδοχείο = the hotel
• του ξενοδοχείου = of the hotel / the hotel’s

Greek often uses the genitive where English might use:

• of the hotel
• the hotel’s

So Η ρεσεψιόν του ξενοδοχείου literally has the structure The reception of the hotel.

This is a normal pattern for many neuter nouns ending in -είο.

Pattern:

• nominative: το ξενοδοχείο
• genitive: του ξενοδοχείου

So the ending changes from -είο to -είου in the genitive singular.

You will see the same pattern with other neuter nouns of this type.

Because the adjective must agree with the noun it describes.

Here, ρεσεψιόν is feminine singular, so the adjective must also be feminine singular:

• masculine: ανοιχτός
• feminine: ανοιχτή
• neuter: ανοιχτό

Since the subject is η ρεσεψιόν, Greek says:

• Η ρεσεψιόν είναι ανοιχτή

not

• Η ρεσεψιόν είναι ανοιχτό

Είναι means is.

In a normal sentence like this, Greek usually includes it:

• Η ρεσεψιόν του ξενοδοχείου είναι ανοιχτή

Greek can sometimes omit the verb to be in headlines, signs, or very compressed styles, but in ordinary full sentences you normally keep είναι.

So here it is the standard, natural choice.

Because όλη means whole / all, and it modifies νύχτα.

So:

• όλη νύχτα = all night / the whole night

The adjective όλη must agree with νύχτα, which is feminine singular. That is why it is όλη.

Compare:

• όλος ο κόσμος = the whole world / everyone
• όλη η μέρα = the whole day
• όλο το βράδυ = the whole evening

Because Greek often leaves out the article in time expressions used adverbially, especially when talking about duration.

So όλη νύχτα works like an adverbial phrase meaning all night.

This is very natural Greek.

You may also hear:

• όλη τη νύχτα

That also means all night and is perfectly natural too. The version without the article is a bit more compact.

It is in the accusative, used adverbially to show duration of time.

So the phrase answers the question for how long?

• όλη νύχτα = for the whole night / all night

This is a very common use of the accusative in Greek with time expressions.

Yes. Όλη τη νύχτα is also correct and very common.

So both are natural:

• όλη νύχτα
• όλη τη νύχτα

The difference is small:

• όλη νύχτα sounds a bit more compact
• όλη τη νύχτα sounds a bit fuller or slightly more explicit

In this sentence, either one would work.

Yes. Both ανοιχτή and ανοικτή mean open.

In modern everyday Greek, ανοιχτή is very common in speech. Ανοικτή is also correct and may sound a bit more formal or conservative in some contexts.

So you could also see:

• Η ρεσεψιόν του ξενοδοχείου είναι ανοικτή όλη νύχτα.

Same meaning.

Not completely. Greek word order is more flexible than English word order.

The sentence as given is the most neutral and straightforward:

• Η ρεσεψιόν του ξενοδοχείου είναι ανοιχτή όλη νύχτα.

But Greek can move parts around for emphasis, for example:

• Η ρεσεψιόν είναι ανοιχτή όλη νύχτα.
• Όλη νύχτα η ρεσεψιόν του ξενοδοχείου είναι ανοιχτή.

That said, the original order is the most natural one for a standard statement.

A rough pronunciation guide is:

ee re-sep-see-ON tou xeno-doh-KHEE-ou EE-ne a-neekh-TEE OH-lee NEEKH-ta

A few useful points:

• χ sounds like a throaty sound, not like English ch
• ει in είναι sounds like ee
• the stress matters in Greek, so pay attention to the accented syllables:
  • ρεσεψιόν
  • ξενοδοχείου
  • είναι
  • ανοιχτή
  • όλη
  • νύχτα

Modern Greek uses many loanwords in everyday life, especially for hotels, tourism, technology, and business.

In this context, ρεσεψιόν is extremely normal and idiomatic. A more descriptive Greek alternative might exist in some situations, but in hotels people very commonly say ρεσεψιόν.

So for a learner, this is a useful real-world word to know.