تبدأ المرحلة اليوم.

A fully vocalized version is:

تبدأُ المرحلةُ اليومَ

A common pronunciation/transliteration is:

tabdaʾu al-marḥalatu al-yawma

Word by word:

• تبدأُ = tabdaʾu
• المرحلةُ = al-marḥalatu
• اليومَ = al-yawma

In normal printed Arabic, those short vowels are usually omitted, so you often just see تبدأ المرحلة اليوم.

تبدأ is the imperfect (non-past/present) form of the verb بدأ, meaning to begin.

In this sentence, تبدأ means begins, is beginning, or even starts, depending on context.

More specifically, it is the 3rd person feminine singular form:

• he begins = يبدأ
• she/it (feminine) begins = تبدأ

Here it matches المرحلة, which is a feminine noun.

Because the subject, المرحلة, is grammatically feminine.

The noun مرحلة ends in ة (tāʾ marbūṭa), which very often marks a feminine noun in Arabic. Since المرحلة is feminine singular, the verb appears in the feminine singular form: تبدأ.

So Arabic is doing agreement here:

• المرحلة تبدأ = the phase begins

Arabic commonly allows verb–subject–other elements word order, especially in neutral written style.

So:

• تبدأ المرحلة اليوم = The phase begins today

This is a very normal Arabic sentence pattern.

You could also say:

• المرحلة تبدأ اليوم

That version is also correct, but it puts a bit more focus on the phase itself. In many contexts, the difference is subtle.

If fully vocalized, the sentence is:

تبدأُ المرحلةُ اليومَ

The endings are:

• تبدأُ: the verb is in the indicative mood
• المرحلةُ: nominative, because it is the subject
• اليومَ: accusative, because it functions as an adverbial expression of time

Even though these endings are important grammatically, they are usually not written in everyday Arabic texts.

اليوم here is an adverbial expression of time, called ظرف زمان in Arabic grammar.

Arabic often expresses time directly without a preposition where English uses words like on, in, or nothing at all depending on the phrase.

So:

• اليومَ = today

You do not need a preposition before it in this sentence.

It can be understood as either present or near future, depending on context.

The imperfect form تبدأ can mean:

• begins
• is beginning
• starts

With اليوم, the sense is often something like:

• The phase begins today
• The phase starts today

So even though the verb is grammatically a present/non-past form, Arabic often uses it for scheduled or contextually clear future events too.

Yes. By itself, تبدأ can also mean you begin when addressing one male.

So out of context, تبدأ can mean either:

• she/it (fem.) begins
• you (masc. singular) begin

But in this sentence, the following noun المرحلة shows that تبدأ is being used as it begins, with المرحلة as the subject.

The root is ب د أ.

The basic past-tense verb is:

• بدأ = he began

The sentence uses the imperfect form:

• تبدأ = she/it begins

The final sound is a hamza because the root itself contains hamza as its third radical. So the hamza is part of the verb, not an extra letter added for some separate reason.

المرحلة is pronounced approximately al-marḥala.

Two useful pronunciation notes:

1. ح is not the ordinary English h.
   It is a deeper, stronger sound made farther back in the throat: ḥ.

2. In المرحلة, the ل of الـ is pronounced clearly.
   That is because م is a moon letter, not a sun letter.

So this word is pronounced:

• al-marḥala not
• am-marḥala

المرحلة can mean stage, phase, or step, depending on context.

Common uses include:

• a stage in a process
• a phase of a project
• an educational level
• a period in development

So in this sentence, the best English meaning depends on the larger context:

• The phase begins today
• The stage begins today

Arabic attaches the definite article directly to the noun as الـ.

So:

• مرحلة = a stage / a phase
• المرحلة = the stage / the phase

Likewise:

• يوم = a day
• اليوم = the day / today depending on context

So Arabic does have the here; it is just attached to the word rather than written separately as in English.