ضغط الدم جيد اليوم.

Because this is a nominal sentence in Arabic, and in the present tense Arabic usually leaves out is / am / are.

So:

• ضغط الدم جيد اليوم = Blood pressure is good today

There is no separate present-tense verb to be here.

If you wanted a different tense, you would usually add a verb, for example:

• كان ضغط الدم جيدًا = Blood pressure was good
• سيكون ضغط الدم جيدًا = Blood pressure will be good

It is an iḍāfa (إضافة), often called a construct phrase.

Literally, it is:

• ضغط = pressure
• الدم = the blood

So the structure is basically pressure of the blood, which is how Arabic expresses blood pressure.

This is very common in Arabic. English often uses noun + noun, while Arabic often uses an iḍāfa instead.

Other examples:

• باب البيت = the door of the house / the house door
• مدير المدرسة = the director of the school / the school principal

That is a normal feature of iḍāfa.

In an iḍāfa:

• the first noun usually does not take الـ
• the second noun can be definite or indefinite

So here:

• ضغط = first noun in the iḍāfa
• الدم = second noun, and it is definite

Because the second noun is definite, the whole phrase ضغط الدم becomes definite: the blood pressure.

Also, the first noun in an iḍāfa does not take tanwīn either.

Here جيد is the predicate of the sentence, not an adjective inside the noun phrase.

The sentence structure is:

• ضغط الدم = the subject
• جيد = the predicate
• اليوم = today

So جيد means good in the sense of is good.

In Arabic nominal sentences, the predicate is often indefinite, so جيد is natural here.

If you said الجيد, it would usually sound more like the good one or a specially identified good thing, which is not what this sentence is doing.

With full case endings, it would be:

• جَيِّدٌ

Because it matches the grammatical head of the subject, which is ضغط.

In ضغط الدم, the main noun is:

• ضغط = pressure

That noun is masculine singular, so the predicate is also masculine singular:

• جيد

Even though the phrase contains الدم, the agreement is with the whole subject phrase, whose head is ضغط.

With full vowel marks, the sentence is:

• ضَغْطُ الدَّمِ جَيِّدٌ اليَوْمَ

Here is why:

• ضَغْطُ: nominative, because it is the subject of the nominal sentence
• الدَّمِ: genitive, because it is the second term of the iḍāfa
• جَيِّدٌ: nominative, because it is the predicate
• اليَوْمَ: accusative as an adverbial expression of time

In normal everyday writing, these case endings are usually not written, so you often just see:

• ضغط الدم جيد اليوم

Yes, it can move.

At the end, it simply means:

• ضغط الدم جيد اليوم = Blood pressure is good today

But Arabic allows some flexibility for emphasis. For example:

• اليوم ضغط الدم جيد = Today, blood pressure is good

This version emphasizes today a bit more.

The original order is a very neutral and natural one.

In writing, it is الدم. But in pronunciation, the ل of الـ assimilates because د is a sun letter.

So it is pronounced more like:

• ad-dam

not al-dam.

This happens with many sun letters. For example:

• الشمس is pronounced ash-shams
• الرجل is pronounced ar-rajul

So in this sentence, الدم is written the normal way, but pronounced with assimilation.

Yes, ضغط is a tough word for many English speakers.

It is roughly:

• ḍaġṭ

The three consonants are:

• ض = an emphatic d-like sound
• غ = a throaty sound, often approximated as gh
• ط = an emphatic t-like sound

A few helpful points:

• The word is short and compact.
• The final consonant cluster can feel heavy.
• Don’t expect it to sound like an English word.

A practical learner approximation is something like dhaght or daght, while you work on the Arabic sounds more precisely.

جيد is perfectly correct and natural in Modern Standard Arabic.

However, in medical contexts, Arabic also often uses words like:

• طبيعي = normal
• مستقر = stable

So you may also hear things like:

• ضغط الدم طبيعي اليوم = Blood pressure is normal today

But for learning basic grammar and sentence structure, ضغط الدم جيد اليوم is completely fine.