تشمل شهادة السلامة السعة القصوى اليوم.

Arabic often allows both:

• Verb + subject + object
• Subject + verb + object

So تشمل شهادة السلامة السعة القصوى اليوم is a normal verb-initial sentence.

A subject-initial version would be:

• شهادة السلامة تشمل السعة القصوى اليوم

Both are grammatical. The verb-initial order is especially common in formal written Arabic.

Because the subject is شهادة (certificate), and شهادة is a feminine singular noun in Arabic.

So the verb must also be feminine singular:

• تشمل = she/it (feminine) includes

Even though certificate is not feminine in English, Arabic nouns have grammatical gender.

This is an iḍāfa construction, often called the genitive/construct phrase.

It works like this:

• شهادة = certificate
• السلامة = safety

Together:

• شهادة السلامة = certificate of safety = safety certificate

Arabic does not use a separate word for of here. The relationship is built directly by putting the two nouns together.

Also, because السلامة is definite (the safety), the whole phrase is definite:

• شهادة السلامة = the safety certificate

This is a noun + adjective phrase:

• السعة = the capacity
• القصوى = maximum / utmost

So:

• السعة القصوى = the maximum capacity

Unlike English, Arabic adjectives usually come after the noun.

Also, the adjective must match the noun in:

• definiteness
• gender
• number
• case

So since السعة is feminine and definite, القصوى is also feminine and definite.

Because القصوى must agree with السعة, and السعة is a feminine noun.

So:

• الأقصى = masculine form
• القصوى = feminine form

Since capacity here is feminine in Arabic, the correct form is:

• السعة القصوى

اليوم means today and functions as a time expression.

In this sentence, it tells you when the action applies:

• تشمل شهادة السلامة السعة القصوى اليوم
• The safety certificate includes the maximum capacity today

Arabic often uses اليوم without a preposition.
So you do not need something like في before it in this kind of sentence.

Its position is fairly flexible. For example:

• اليوم تشمل شهادة السلامة السعة القصوى
• تشمل شهادة السلامة اليوم السعة القصوى
• تشمل شهادة السلامة السعة القصوى اليوم

All are possible, though the emphasis shifts a little.

In this sentence:

• تشمل = verb
• شهادة السلامة = subject
• السعة القصوى = object
• اليوم = time expression

So the structure is:

• includes
  • the safety certificate
    • the maximum capacity
      • today

If the sentence is fully vowelled, the case endings help show this more clearly:

• تَشْمَلُ شَهَادَةُ السَّلَامَةِ السِّعَةَ القُصْوَى اليَوْمَ

Here:

• شهادةُ has nominative -u as the subject
• السعةَ has accusative -a as the object
• اليومَ is also accusative as an adverbial time expression

In normal unvowelled writing, you usually figure this out from word order and meaning.

No. تشمل can also mean things like:

• include
• cover
• encompass
• involve

The best English translation depends on context.

For official or formal language, تشمل is very common when talking about what a document, law, policy, or report contains or covers.

Grammatically, it is fine.

But depending on the exact meaning, it may sound a bit formal or slightly context-dependent, especially because today can feel a little abrupt at the end.

If the intended meaning is something like as of today, Arabic might sometimes express that more explicitly, for example:

• تشمل شهادة السلامة السعة القصوى اعتبارًا من اليوم
• The safety certificate includes the maximum capacity starting today / as of today

If the simple meaning is just today, the original sentence is still understandable.