بعض الناس يفضلون القهوة.

Because بعض usually forms an iḍāfa construction with the noun after it:

• بعض الناس
• literally: some of the people
• idiomatically in English: some people

In Arabic, the second noun in this structure is often definite when it refers to a whole class or group. So الناس means the people / people in general, and بعض الناس means some of those people, which is the normal way to say some people.

بعض means some, part of, or a portion of depending on context.

In this sentence, it means some:

• بعض الناس = some people

But in other contexts it can be more literal:

• بعض الماء = some of the water
• بعض الكتاب = part of the book

So بعض is a very flexible word, but the basic idea is always a part of a larger whole.

Because the subject refers to more than one person: بعض الناس.

Here the subject comes before the verb, and in that word order, the verb normally shows full agreement in Modern Standard Arabic. So:

• بعض الناس يفضلون القهوة
• Some people prefer coffee

The ending ـون in يفضلون marks they (masculine plural / mixed plural).

Even though بعض by itself is grammatically singular in form, the phrase بعض الناس refers to a plural group, so plural agreement is natural here.

Yes. That is also a correct and very common MSA word order.

Compare:

• بعض الناس يفضلون القهوة
  subject first, then verb
• يفضل بعض الناس القهوة
  verb first, then subject

In formal MSA, when the verb comes first, it is often singular with a plural subject that follows it, so يفضل بعض الناس is normal.

So both are correct, but the agreement pattern changes with word order:

• بعض الناس يفضلون... → plural verb
• يفضل بعض الناس... → usually singular verb

Arabic often uses the definite article for generic meaning.

So القهوة here does not necessarily mean one specific coffee. It usually means coffee as a type of drink or coffee in general.

That is very common in Arabic:

• أحب الشاي = I like tea
• يفضلون القهوة = They prefer coffee

In English, generic nouns often appear without the, but Arabic often uses الـ for that purpose.

With full case endings, it would be:

بعضُ الناسِ يُفَضِّلونَ القهوةَ

Here is why:

• بعضُ → nominative, because it is the subject
• الناسِ → genitive, because it is the second part of an iḍāfa after بعض
• يُفَضِّلونَ → verb, so it does not take noun case endings
• القهوةَ → accusative, because it is the direct object

In normal writing, these short vowel endings are usually omitted.

الناس means people, so semantically it is plural.

It is not a regular sound plural like مسلمون or طالبات. It is a very common collective noun meaning people / mankind / humans, depending on context.

Its usual singular equivalent in meaning is not ناس by itself in standard usage, but rather words like:

• إنسان = human being
• شخص = person

So learners should just memorize الناس as the normal word for people.

The verb is from فَضَّلَ meaning to prefer.

Its forms here are:

• past: فَضَّلَ = he preferred
• present/imperfect: يُفَضِّلُ = he prefers
• plural: يُفَضِّلون = they prefer

So يفضلون is:

• present/imperfect tense
• third person
• masculine plural / mixed plural

The basic pattern here is Form II, which often has a doubled middle consonant in pronunciation:

• يُفَضِّلون

No. The verb already includes that meaning.

The ending ـون tells you the subject is they (masculine plural or mixed plural), so Arabic does not need a separate pronoun here.

That is why:

• يفضلون already means they prefer

Arabic can still mention the subject explicitly, as in:

• بعض الناس يفضلون القهوة

This is not wrong or redundant. It simply identifies who they are.

Usually, for this meaning, بعض الناس is the natural choice.

بعض من الناس is possible in some contexts, but it is less neutral and often more emphatic or stylistically marked. It can sound like some among the people.

For everyday MSA, if you want to say some people, use:

• بعض الناس

A careful pronunciation with vowels is:

baʿḍu an-nāsi yufaḍḍilūna al-qahwata

A few pronunciation notes:

• بعض has the consonant ʿayn in the middle: baʿḍ
• الناس is pronounced an-nās, because ن is a sun letter, so the ل of الـ is not pronounced
• يفضلون is pronounced yufaḍḍilūn
• القهوة is al-qahwa in pause, or al-qahwata with full case ending

In normal speech without case endings, you would often hear something close to:

• baʿḍ an-nās yufaḍḍilūn al-qahwa

Most naturally, it means coffee in general.

Because القهوة is being used generically, the sentence is understood as:

• Some people prefer coffee

If you wanted to talk about a specific coffee in context, the same form could also do that, but without extra context, the generic meaning is the default here.