وصفة النظارة جاهزة بالتأكيد.

Because Arabic often leaves out the present-tense to be in simple statements.

So:

• وصفة النظارة جاهزة
  literally: The glasses prescription ready
• natural English: The glasses prescription is ready

This is a very common pattern in Arabic. In the present tense, you usually do not say a separate word for is / are / am.

If you wanted the past, you would use a verb, for example:

• كانت وصفة النظارة جاهزة = The glasses prescription was ready

It is a nominal sentence.

It begins with a noun phrase:

• وصفة النظارة = the glasses prescription / the prescription for the glasses

Then it is followed by a predicate:

• جاهزة = ready

So the basic structure is:

• subject/topic: وصفة النظارة
• predicate/comment: جاهزة

Then بالتأكيد adds emphasis: definitely / certainly.

It is an iḍāfa construction, often called a genitive construction or annexation.

Structure:

• وصفة = prescription
• النظارة = the glasses

Together:

• وصفة النظارة = the prescription of the glasses
• more natural English: the glasses prescription or the prescription for the glasses

In an iḍāfa:

• the first noun usually does not take ال
• the second noun can be definite, and that makes the whole phrase definite

So because النظارة is definite, وصفة النظارة is understood as definite too.

Because in an iḍāfa construction, the first noun normally does not take ال.

So you say:

• وصفة النظارة

not:

• الوصفة النظارة

That is one of the key rules of iḍāfa.

The definiteness comes from the second noun:

• نظارة = glasses / eyeglasses
• النظارة = the glasses

Since the second part is definite, the whole phrase becomes definite:

• وصفة النظارة = the glasses prescription

Because it agrees with وصفة, which is a feminine singular noun.

• وصفة is feminine
• so the adjective/predicate must also be feminine singular
• therefore: جاهزة

Compare:

• الكتاب جاهز = The book is ready.
  (كتاب is masculine)
• الوصفة جاهزة = The prescription is ready.
  (وصفة is feminine)

Even though النظارة is also feminine, the agreement here is with the head noun of the phrase, which is وصفة.

بالتأكيد means certainly, definitely, or for sure.

It is made of:

• بـ = with / by / in
• التأكيد = confirmation / certainty / emphasis

So literally it comes from something like with certainty / with confirmation, but in normal English it is best translated as:

• definitely
• certainly

In this sentence:

• وصفة النظارة جاهزة بالتأكيد = The glasses prescription is definitely ready

Yes. Arabic often allows some flexibility with adverb-like expressions such as بالتأكيد.

Possible placements include:

• وصفة النظارة جاهزة بالتأكيد
• وصفة النظارة بالتأكيد جاهزة
• بالتأكيد وصفة النظارة جاهزة

The nuance can shift slightly depending on emphasis, but all can mean roughly The glasses prescription is definitely ready.

The version you have is very natural and places the certainty at the end.

Yes, it can.

In modern usage, نظارة often refers to eyeglasses / glasses as a single item, even though English treats glasses as plural in form.

So:

• نظارة = eyeglasses / a pair of glasses
• وصفة النظارة = eyeglass prescription / glasses prescription

This is one of those places where Arabic and English package the idea differently.

The final ة is called tāʾ marbūṭa.

In pause, when stopping at the word, it is usually pronounced like -a / -ah:

• وصفة ≈ waṣfa
• جاهزة ≈ jāhiza

But when the word is followed by grammatical endings in full formal pronunciation, the t sound can appear.

For a learner reading normal MSA aloud, it is enough to know:

• at the end of the word in ordinary speech: usually -a
• in connected grammatical reading: it may behave like t

Because Arabic is very often written without full short vowels and case endings in ordinary text.

So you see:

• وصفة النظارة جاهزة بالتأكيد

In fully vowelled formal Arabic, the case endings could be shown, for example:

• وصفةُ النظارةِ جاهزةٌ بالتأكيدِ

But in normal writing, these are usually omitted, and native readers understand them from context.

For a learner, the important thing is the structure:

• وصفةُ = subject
• النظارةِ = second part of iḍāfa
• جاهزةٌ = predicate

Yes. That is a reasonable translation.

Depending on context, وصفة النظارة could be rendered as:

• the glasses prescription
• the eyeglass prescription
• the prescription for the glasses

And بالتأكيد could be:

• definitely
• certainly
• for sure

So several natural English translations are possible, for example:

• The eyeglass prescription is definitely ready.
• The prescription for the glasses is certainly ready.

A very natural way would be:

• وصفة النظارة ليست جاهزة بعد.

Breakdown:

• ليست = is not (for feminine singular in a nominal sentence)
• جاهزة = ready
• بعد = yet

So:

• وصفة النظارة ليست جاهزة بعد = The glasses prescription is not ready yet

This is useful because it shows the same agreement pattern:

• وصفة is feminine
• so the negative form uses ليست rather than ليس