لازم است که برای ناهار برنج بخریم.

لازم است means it is necessary or it is needed. In this sentence, it expresses obligation, so the whole sentence means something like It is necessary for us to buy rice for lunch.

A very natural English equivalent is We need to buy rice for lunch.

که introduces the clause that follows لازم است. It works a bit like that in English:

• لازم است که ...
• It is necessary that ...

So:

• لازم است که برای ناهار برنج بخریم
• It is necessary that we buy rice for lunch

In everyday English, that is often omitted, and the same is often true in Persian.

Yes. Very often, Persian speakers omit که after expressions like لازم است.

So both are natural:

• لازم است که برای ناهار برنج بخریم
• لازم است برای ناهار برنج بخریم

Both mean the same thing.

بخریم is a subjunctive/present subjunctive form. After expressions of necessity, desire, possibility, suggestion, and similar ideas, Persian often uses this form.

Here, لازم است creates that kind of meaning, so the verb becomes:

• بخریم = that we buy / for us to buy

By contrast:

• می‌خریم means we buy / we are buying / we will buy in a more indicative, factual sense

So:

• لازم است که برنج بخریم = It is necessary that we buy rice
• برنج می‌خریم = We buy rice / We are buying rice

The subject we is built into the verb ending -یم in بخریم.

Breakdown:

• بخر- = buy
• -یم = we

So بخریم means we buy in the subjunctive sense.

Persian often does not need a separate subject pronoun when the verb ending already shows the subject clearly.

If you wanted, you could say ما بخریم, but it is usually unnecessary unless you want emphasis.

That بـ is part of the subjunctive form. In many present subjunctive verbs in Persian, you see:

• بـ + present stem + personal ending

For خریدن (to buy), the present stem is خر.

So:

• بخرم = I buy / that I buy
• بخری = you buy / that you buy
• بخریم = we buy / that we buy

That is why the sentence uses بخریم.

The infinitive is خریدن, meaning to buy.

Its present stem is خر. From that stem, you make forms like:

• می‌خرم = I buy
• می‌خریم = we buy
• بخریم = that we buy / let us buy / we should buy, depending on context

So بخریم comes from خریدن.

Persian normally puts the verb at the end of the clause, so it often follows a pattern like:

• subject
• other information
• object
• verb

Here:

• برای ناهار = for lunch
• برنج = rice
• بخریم = we buy

So the order is completely normal for Persian.

A more literal word-for-word order would be:

• It is necessary that for lunch rice buy-we

That sounds odd in English, but it is natural in Persian.

Because برنج here is a non-specific direct object.

In Persian, را is usually used with specific direct objects. Compare:

• برنج بخریم = buy rice / buy some rice
• برنج را بخریم = buy the rice / buy that specific rice

In this sentence, the meaning is general: we need to buy rice for lunch, not a particular already-identified rice. So leaving out را is normal.

برای means for, and ناهار means lunch.

So برای ناهار means for lunch.

It tells us the purpose of buying the rice:

• not just buying rice in general
• but buying it for lunch

A common pronunciation is:

lāzem ast ke barāye nāhār berenj bekharim

A few notes:

• لازم = lāzem
• است = ast
• برای = barāye
• ناهار = nāhār
• برنج = berenj
• بخریم = bekharim

In normal speech, some speakers may say it a bit more smoothly or casually, but this pronunciation is a good standard guide.

Yes. A very common alternative is:

• باید برای ناهار برنج بخریم

This also means We need to buy rice for lunch or We must buy rice for lunch.

Compared with لازم است که ..., باید ... is often more direct and more common in everyday speech.

A colloquial version of the original sentence might also sound like:

• لازمه که برای ناهار برنج بخریم

Here, لازمه is the spoken form of لازم است.

It usually refers to a needed action from now forward, so in English it often feels like future:

• We need to buy rice for lunch

Even though the Persian verb is a present subjunctive form, the meaning is not we are buying rice right now. It is about what needs to happen.

So the sense is:

• It is necessary now
• that we buy rice before lunch / for lunch

Not by itself. Because of لازم است, the sentence clearly means it is necessary that we buy rice for lunch.

However, بخریم by itself can sometimes appear in contexts that feel like let’s buy:

• برنج بخریم؟ = Shall we buy rice? / Let’s buy rice?

So the form بخریم can have different shades depending on context, but in this sentence the necessity comes from لازم است.

In Persian, mass nouns like rice usually stay singular-looking, just as in English we normally say rice, not rices.

So:

• برنج = rice

If you want to talk about types of rice, that is a different situation, but in this sentence برنج simply means rice as a food item.

So برنج بخریم is exactly what you would expect for buy rice.