السنة تبدأ اليوم.

Because السنة (the year) is a feminine singular noun in Arabic, and the verb agrees with it in gender.

• السنة = feminine
• تبدأ = she/it begins or it starts for a feminine singular subject

So:

• السنة تبدأ اليوم = The year starts today

If the subject were a masculine noun, you would usually expect يبدأ instead.

Yes. سنة is grammatically feminine in Arabic.

One clue is the ending ـة (tāʾ marbūṭa), which very often marks feminine nouns:

• سنة = year
• مدرسة = school
• مدينة = city

So even though year is not feminine in English, Arabic treats سنة as feminine, and the verb must match that.

Literally, it is:

• السنة = the year
• تبدأ = begins / starts
• اليوم = today

So the word order is:

• The year begins today

This is very close to normal English word order in this case.

Because Arabic normally does not use a present-tense form of to be in simple sentences like this.

In English, you often need is, are, etc.
In Arabic, the present tense usually leaves that out.

But in this sentence, there is already a main verb:

• تبدأ = begins / starts

So there is no need for is anyway.

Compare:

• السنة جديدة = The year is new
  Arabic has no written is here.
• السنة تبدأ اليوم = The year begins today
  Here the main verb is تبدأ.

تبدأ comes from the root ب د أ, which is connected with the idea of beginning or starting.

A common past form is:

• بدأ = he began

Related forms include:

• يبدأ = he/it begins
• تبدأ = she/it begins or you begin depending on context
• بداية = beginning

In your sentence, تبدأ means it begins, referring to السنة.

Because of the context and the subject written in the sentence.

تبدأ can mean different things in Arabic depending on context, including:

• she begins
• it begins (for a feminine noun)
• you begin (addressing one person)

But here, the sentence already has the subject:

• السنة = the year

So تبدأ must match that subject, and the meaning is:

• The year begins / starts today

In many contexts, اليوم literally means the day, but it is also very commonly used idiomatically to mean today.

So in this sentence:

• اليوم = today

This is very natural Arabic.

Depending on context, اليوم can also mean:

• today
• this day
• the day

But here today is the natural meaning.

That is just how this expression works in Arabic. The word اليوم includes the definite article الـ, but it can still mean today.

So learners should think of اليوم as a common fixed expression meaning today, even though literally it looks like the day.

This kind of thing is normal in languages: the literal form and the usual meaning are not always exactly the same.

A careful pronunciation would be:

as-sanatu tabdaʾu al-yawma

A few notes:

• السنة is pronounced roughly as-sanah in pause, or as-sanatu with full case ending
• The ل in الـ assimilates before س, so السنة sounds like as-sana..., not al-sana...
• تبدأ contains a hamza (ء), a glottal stop, in the middle: tab-da-ʾu
• اليوم is roughly al-yawm or al-yawma with full ending

In normal spoken reading, many final short vowels are not pronounced, so you will often hear something close to:

as-sana tabdaʾ al-yawm

In fully vocalized Modern Standard Arabic, it would typically be:

السَّنَةُ تَبْدَأُ الْيَوْمَ

Why these endings?

• السنةُ: nominative, because it is the subject/topic of the sentence
• تبدأُ: present tense verb in the indicative
• اليومَ: accusative as an adverb of time (ظرف زمان)

In everyday writing, these short vowels are usually omitted, so you normally see:

السنة تبدأ اليوم

It is usually analyzed as a nominal sentence because it starts with a noun:

• السنة = the topic / subject
• تبدأ اليوم = the predicate, which is a verbal clause

So the structure is roughly:

• [The year] [begins today]

If the sentence started with the verb, like تبدأ السنة اليوم, that would clearly be a verbal sentence.

Yes. تبدأ السنة اليوم is also correct.

Both are grammatical, but the emphasis is slightly different:

• السنة تبدأ اليوم: puts more focus on the year
• تبدأ السنة اليوم: starts with the action begins

In many cases, both would translate naturally as:

• The year begins today

Arabic allows more flexibility in word order than English, though the choice can affect style or emphasis.

Both سنة and عام can mean year, but they are not always used in exactly the same way.

In many everyday contexts, they overlap a lot. For example:

• السنة = the year
• العام = the year

However, learners often notice that سنة is feminine and عام is masculine, so verb agreement changes:

• السنة تبدأ اليوم
• العام يبدأ اليوم

Both can mean The year begins today, but the verb changes because:

• السنة is feminine → تبدأ
• العام is masculine → يبدأ

Because ـة is tāʾ marbūṭa, a special ending often used for feminine nouns.

Its pronunciation changes depending on context:

• In pause, it usually sounds like -a / -ah
  • سنة → sanah
• When followed by grammatical endings or in connected formal reading, the t sound appears
  • السنةُ → as-sanatu

So the same spelling can sound slightly different depending on how carefully the sentence is read.

It can often cover both, depending on context.

The Arabic present tense can express:

• a simple present: begins
• an ongoing action: is beginning
• sometimes a near future, depending on context

In this sentence, the most natural English translation is:

• The year begins today
• or The year starts today

That is usually better than is beginning today, unless the context specifically calls for that nuance.