لم يعد وعاء الطعام فارغا.

Here, لم يعد means is no longer or is not ... anymore.

So the sentence means that the food container used to be empty, but that is no longer true.

This is a very common Arabic pattern:

• لم يعد الجو باردًا = The weather is no longer cold.
• لم تعد المشكلة بسيطة = The problem is no longer simple.

Even though عاد can literally mean returned, in this structure it often means ceased to be / no longer is.

Yes. Context decides.

For example:

• لم يعد إلى البيت = He did not return home.

But in your sentence, لم يعد is followed by:

• a noun phrase: وعاء الطعام
• and then an adjective/predicate: فارغًا

That structure strongly suggests the meaning is no longer empty, not did not return.

It is pronounced yaʿud, so:

• لم يعد = lam yaʿud

It is not pronounced yaʿīd here.

Why? Because the verb is from عاد / يعود. After لم, the imperfect verb becomes jussive, so يعودُ becomes يَعُدْ.

So:

• يعودُ → he returns / he goes back
• لم يَعُدْ → he did not return / he is no longer

Because لم always goes with the imperfect verb in Arabic and makes it jussive.

So grammatically, Arabic uses:

• لم + imperfect verb

But the meaning is usually negative past, or in expressions like لم يعد, it often gives the idea no longer.

So this is normal Arabic grammar, even if English uses a different tense structure.

It is a verbal sentence, because it begins with a verb:

• لم يعد

Then comes the subject-like noun phrase:

• وعاء الطعام

Then the predicate:

• فارغًا

So the structure is roughly:

• لم يعد
  • وعاء الطعام
    • فارغًا
• is no longer
  • the food container
    • empty

وعاء الطعام is an iḍāfa construction, often called a genitive/possessive construction.

It literally means:

• وعاء = container, vessel
• الطعام = the food

So literally: container of the food

In natural English, that becomes the food container or the container for food, depending on context.

Because in an iḍāfa, the first noun usually does not take الـ.

So Arabic says:

• وعاء الطعام

not usually:

• الوعاء الطعام

The whole phrase becomes definite because the second noun is definite:

• الطعام = the food

So وعاء الطعام means the food container, not just a food container.

The fully vowelled form is فارغًا.

This word is in the accusative here, so it takes fatḥa and tanwīn fatḥ:

• فارغًا = empty

In normal unvowelled writing, that often appears as:

• فارغا

The extra ا is the usual spelling for tanwīn fatḥ in many words.

Because عاد here works like one of the كان وأخواتها-type verbs when it means to become / to be again / to continue in a state.

That means:

• its subject is nominative
• its predicate is accusative

So in this sentence:

• وعاءُ الطعامِ = nominative
• فارغًا = accusative

That is why the adjective is not nominative here.

A fully vowelled version is:

لَمْ يَعُدْ وِعاءُ الطَّعامِ فارِغًا

Breakdown:

• لَمْ = negation particle
• يَعُدْ = jussive imperfect of عاد
• وِعاءُ = nominative
• الطَّعامِ = genitive, because it is the second part of the iḍāfa
• فارِغًا = accusative predicate

Yes. You could also say:

وعاء الطعام لم يعد فارغًا

That is also correct.

The difference is mostly about emphasis and style:

• لم يعد وعاء الطعام فارغًا = more neutral, standard verbal opening
• وعاء الطعام لم يعد فارغًا = puts more focus on the food container

Both are natural in Modern Standard Arabic.

The difference is in meaning:

• ليس وعاء الطعام فارغًا = The food container is not empty.
• لم يعد وعاء الطعام فارغًا = The food container is no longer empty.

So ليس just says the container is not empty now.

But لم يعد adds a sense of change: it suggests that it was empty before, but that has changed.