وصفة النظارة جاهزة.

Because this is a present-tense nominal sentence in Arabic. In Arabic, the present-tense verb to be is usually not stated.

So the structure is simply:

• وصفة النظارة = the glasses prescription
• جاهزة = ready

Arabic literally says something like The glasses prescription ready, and English supplies is.

If you wanted a past meaning, Arabic would normally use a verb such as كانت:

• وصفة النظارة كانت جاهزة = The glasses prescription was ready

Because it matches وصفة, and وصفة is a feminine noun.

In Arabic, adjectives and predicate adjectives normally agree with the noun they describe in gender and number.

• وصفة = feminine
• جاهزة = feminine form of ready

If the noun were masculine, you would expect جاهز instead.

Because جاهزة here is the predicate of the sentence, not an adjective inside the noun phrase.

Compare:

• وصفة النظارة جاهزة = The glasses prescription is ready.
• وصفة النظارة الجاهزة = the ready glasses prescription

In Arabic, the predicate in a sentence like this is usually indefinite, so it appears without ال.

It is an iḍāfa construction, the very common Arabic noun-noun structure often used for possession or close relationships.

Here:

• وصفة = prescription
• النظارة = the glasses

Together, وصفة النظارة means something like:

• the glasses prescription
• the prescription for the glasses

Important things about iḍāfa:

• The first noun usually does not take ال
• The second noun can be definite
• If the second noun is definite, the whole phrase is definite

So وصفة النظارة is definite even though وصفة itself has no ال.

Because it ends in ـة, called tāʾ marbūṭa.

When a word with ـة is said by itself in pause, it is usually pronounced like -a or -ah. But when it is followed directly by another word in connected grammar, especially in an iḍāfa, the t sound appears.

So:

• by itself: وصفة ≈ waṣfa
• in this sentence: وصفة النظارة ≈ waṣfat ...

That is why learners often hear a t even though the word seems to end with -a.

Because ن is a sun letter.

With sun letters, the l sound of ال assimilates to the first consonant of the word in pronunciation.

So:

• written: النظارة
• pronounced: roughly an-naẓẓāra

The spelling stays the same, but the pronunciation changes.

Because Arabic and English do not always package meaning the same way.

English usually uses the plural word glasses for one wearable pair. Arabic commonly uses the singular feminine noun نظارة for a pair of glasses or eyeglasses.

So وصفة النظارة is natural Arabic even though English uses a plural-looking word.

If you used نظارات, that would usually suggest multiple glasses or multiple pairs.

Yes. وصفة is a flexible word. Depending on context, it can mean:

• recipe
• prescription
• formula
• set of instructions

In this sentence, because of النظارة, the intended meaning is clearly prescription, specifically an eyeglasses prescription.

So context is what tells you which meaning is meant.

It would be:

وَصْفَةُ النَّظَّارَةِ جَاهِزَةٌ

Here is the grammar behind the endings:

• وَصْفَةُ = nominative, because it is the subject of the nominal sentence
• النَّظَّارَةِ = genitive, because it is the second noun in the iḍāfa
• جَاهِزَةٌ = nominative, because it is the predicate

In everyday speech, these case endings are often not pronounced, but in careful MSA grammar they are there.