Τον Δεκέμβριο γιορτάζουμε τα Χριστούγεννα και το σπίτι μυρίζει γλυκά και καφέ.

Because Greek often uses the accusative to express time, especially for months and dates.

• ο Δεκέμβριος = December (dictionary form, nominative)
• τον Δεκέμβριο = in December / during December

So in this sentence, Τον Δεκέμβριο means in December.

This is very common:

• Τον Ιανουάριο = in January
• Την Κυριακή = on Sunday
• Το καλοκαίρι = in the summer

The article changes too:

• nominative: ο Δεκέμβριος
• accusative: τον Δεκέμβριο

In Greek, the verb ending often already shows the subject, so a separate subject pronoun is usually unnecessary.

• γιορτάζω = I celebrate
• γιορτάζεις = you celebrate
• γιορτάζει = he/she/it celebrates
• γιορτάζουμε = we celebrate

So γιορτάζουμε by itself already means we celebrate.

Greek uses subject pronouns like εγώ, εσύ, εμείς mainly for emphasis or contrast:

• Εμείς γιορτάζουμε... = We celebrate... (emphatic)

γιορτάζουμε is:

• present tense
• active voice
• 1st person plural
• from the verb γιορτάζω = celebrate

In this sentence, the present tense expresses a general or habitual idea:

• Τον Δεκέμβριο γιορτάζουμε τα Χριστούγεννα = In December we celebrate Christmas

This is not necessarily about this exact moment; it is more like a regular fact.

In Greek, Χριστούγεννα is a neuter plural noun, even though in English Christmas is treated as singular.

So Greek says:

• τα Χριστούγεννα = Christmas

This is just how the word works in Greek. You should learn it as a fixed expression.

Examples:

• Τα Χριστούγεννα είναι τον Δεκέμβριο. = Christmas is in December.
• Γιορτάζουμε τα Χριστούγεννα με την οικογένεια. = We celebrate Christmas with the family.

Greek uses the definite article much more often than English does.

• το σπίτι literally = the house / the home

In this sentence, it refers to the home in a general but definite way, so Greek naturally uses the article:

• το σπίτι μυρίζει... = the house/home smells...

In English, we might sometimes say the house smells... or just the house/home smells like..., but Greek strongly prefers the article here.

It can mean either, depending on context.

• house when talking about the building
• home when talking about the place where people live

In this sentence, το σπίτι μυρίζει γλυκά και καφέ could be understood as:

• the house smells of sweets and coffee
• or more naturally in English, the home smells of sweets and coffee

So the exact English choice depends on tone and context.

This is a very common difference between Greek and English.

The verb μυρίζω / μυρίζει can take a direct object-like noun to express what something smells of.

So:

• Το σπίτι μυρίζει γλυκά και καφέ. literally = The house smells sweets and coffee but naturally in English = The house smells of sweets and coffee or The house smells like sweets and coffee

Greek does not need a preposition here.

You will often see this pattern:

• Μυρίζει λουλούδια. = It smells of flowers.
• Μυρίζει βανίλια. = It smells of vanilla.

Here γλυκά is a noun, not an adjective.

It means:

• sweets
• desserts
• pastries, depending on context

It comes from the adjective γλυκός / γλυκιά / γλυκό = sweet, but το γλυκό can also mean a sweet / dessert.

Plural:

• το γλυκό = sweet / dessert
• τα γλυκά = sweets / desserts

So in this sentence:

• το σπίτι μυρίζει γλυκά = the house smells of sweets/desserts

Because the sentence is talking about smells in a general, substance-like way, not specific identifiable items.

So:

• γλυκά = sweets
• καφέ = coffee

Without articles, they sound more natural here, like English smells of sweets and coffee.

If you added articles, it could sound more specific or different in nuance:

• μυρίζει τα γλυκά might suggest the smell of specific sweets
• μυρίζει τον καφέ could suggest a particular coffee

But in this sentence, the article-less form is the natural general expression.

Here καφέ is the noun coffee.

The basic dictionary form is:

• ο καφές = coffee

In this sentence, after μυρίζει, Greek commonly uses the form καφέ:

• μυρίζει καφέ = smells of coffee

This is a very natural expression.

So even though the full noun is ο καφές, in this structure you often see:

• καφέ rather than
• καφές

Because the sentence joins two different things:

1. two clauses:
   • γιορτάζουμε τα Χριστούγεννα
   • το σπίτι μυρίζει γλυκά και καφέ

These are linked by the first και:

• ...τα Χριστούγεννα και το σπίτι μυρίζει... = ...Christmas and the house smells...

2. two nouns inside the second clause:
   • γλυκά
   • καφέ

These are linked by the second και:

• γλυκά και καφέ = sweets and coffee

So each και has its own job.

Yes. Greek word order is more flexible than English word order, although some versions sound more natural than others.

The given sentence:

• Τον Δεκέμβριο γιορτάζουμε τα Χριστούγεννα και το σπίτι μυρίζει γλυκά και καφέ.

This begins with Τον Δεκέμβριο to set the time first: In December...

You could also say:

• Γιορτάζουμε τα Χριστούγεννα τον Δεκέμβριο...

But the original order sounds very natural because it gives the time frame immediately.

Greek often moves elements around for emphasis, topic, or style.

It is most naturally understood as a general/habitual statement.

Even though the verb is in the present tense:

• γιορτάζουμε
• μυρίζει

the meaning is not necessarily right now at this exact moment. It means something like:

• In December, we celebrate Christmas, and the house smells of sweets and coffee.

This is a typical use of the Greek present tense for regular events, traditions, and general truths.