هذا كلام واضح.

It is a nominal sentence in Arabic, meaning a sentence that does not need a verb like to be in the present tense.

A simple way to read its structure is:

• هذا = this
• كلام واضح = clear speech / clear talk

So the whole sentence works like:

• This is clear speech.

In Arabic, the verb to be is usually not expressed in the present tense.

So Arabic says:

• هذا كلام واضح

where English says:

• This is clear speech

But in the past or future, Arabic would use a verb such as كان or سيكون, depending on the meaning.

هذا is the masculine singular demonstrative meaning this.

It is used with nouns that are grammatically masculine singular. Since كلام is treated as masculine singular, هذا is the correct form.

Compare:

• هذا = this (masculine singular)
• هذه = this (feminine singular)

This is a very common learner question.

هذا is pronounced hādhā. In fully vocalized writing, you may see a small mark above the هـ called a dagger alif:

• هٰذا

That little mark shows the long ā sound.

So even though the ordinary spelling is هذا, the pronunciation is still:

• hā-dhā

Also, ذ is pronounced like the th in this, not like z or d.

These are two different patterns with two different meanings:

• هذا كلام واضح = This is clear speech / This is clear talk
• هذا الكلام واضح = This speech / this talk is clear

In the sentence you gave, كلام واضح is the predicate phrase, so كلام is indefinite.

A useful contrast:

• هذا بيت كبير = This is a big house
• هذا البيت كبير = This house is big

So the absence or presence of ال changes the structure and meaning.

Because in Arabic, adjectives normally come after the noun they describe.

So:

• كلام واضح = clear speech
  • كلام = speech
  • واضح = clear

This is the normal noun + adjective order in Arabic.

Because it is describing an indefinite noun: كلام.

In Arabic, adjectives match the nouns they describe in several ways, including definiteness.

So:

• كلام واضح = clear speech
  both are indefinite

But:

• الكلام الواضح = the clear speech
  both are definite

This matching is very important in Arabic.

واضح agrees with كلام in the normal adjective way.

Here, كلام is:

• masculine
• singular
• indefinite

So the adjective is also:

• masculine singular
• indefinite

That is why you get:

• كلام واضح

and not a feminine form like واضحة.

In fully vocalized Arabic, it would typically be:

• هٰذا كلامٌ واضحٌ

The ending -ٌ shows nominative indefinite.

In normal everyday writing, these short-vowel endings are usually omitted, so you simply see:

• هذا كلام واضح

When reading aloud in pause, learners often pronounce it more simply as:

• hādhā kalām wāḍiḥ

But in careful grammatical reading, it is:

• hādhā kalāmun wāḍiḥun

Grammatically, yes: it is treated as masculine singular.

In meaning, though, it often behaves like a mass noun in English, similar to speech, talk, or words in a general sense.

So even though it does not always refer to just one countable item, Arabic still treats it as singular for agreement here.

That is why the sentence uses:

• هذا
• واضح

both in masculine singular form.

Yes.

هذا كلام واضح is a full sentence:

• This is clear speech

If you want the noun phrase this clear speech, Arabic would normally make the noun definite:

• هذا الكلام الواضح

So the difference is:

• هذا كلام واضح = sentence
• هذا الكلام الواضح = noun phrase

This is an important distinction in Arabic.