Questa malattia è grave.

Because malattia is a feminine singular noun in Italian. Demonstratives like this must agree with the noun they modify:

• questo = this (masculine singular)
• questa = this (feminine singular)

Since malattia is feminine, you say questa malattia = this illness/disease.

A common clue is the ending: many Italian nouns ending in -a are feminine. Malattia is one of them.

So:

• la malattia = the illness
• questa malattia = this illness

As always, there are exceptions in Italian, but here the -a ending matches the feminine gender.

The accent is important because è means is, from the verb essere.

Without the accent, e means and.

So:

• è = is
• e = and

That little accent changes the meaning completely.

È is the third person singular present of essere (to be).

The present tense forms are:

• io sono = I am
• tu sei = you are
• lui/lei è = he/she is
• noi siamo = we are
• voi siete = you all are
• loro sono = they are

In Questa malattia è grave, the subject is singular, so è is the correct form.

It actually already works for both masculine and feminine singular. Grave is an adjective with the same singular form for masculine and feminine:

• un problema grave = a serious problem
• una malattia grave = a serious illness

But in the plural it changes:

• problemi gravi
• malattie gravi

So grave agrees with the noun, but the masculine and feminine singular happen to look the same.

The plural would be:

Queste malattie sono gravi.

Breakdown:

• questa → queste
• malattia → malattie
• è → sono
• grave → gravi

Everything that needs to agree changes to plural.

In Italian, adjectives often come after the noun, especially when they are descriptive and straightforward.

So:

• malattia grave = serious illness

This is very normal Italian word order. English often puts adjectives before the noun, but Italian commonly places them after.

In this sentence, grave comes after the verb because it is a predicate adjective:

• Questa malattia è grave. Literally: This illness is serious.

Yes. In many contexts, malattia can be translated as illness, disease, or sickness, depending on the situation.

So Questa malattia è grave could be understood as:

• This illness is serious
• This disease is serious

The exact English choice depends on context.

A simple pronunciation guide is:

KWEH-sta ma-la-TEE-a eh GRAH-veh

A few notes:

• qu in questa sounds like kw
• gli is not in this sentence, so nothing tricky there
• ti in malattia is a normal tee
• the stress in malattia is on -ti-
• grave has two syllables: GRA-ve

A more natural flow is: KWEH-sta ma-la-TEE-a eh GRAH-veh

No, that would not sound correct here.

You could say:

• Questa malattia è grave. = This illness is serious.
• La malattia è grave. = The illness is serious.

But Malattia è grave without an article or determiner is not normal in this kind of sentence. Italian usually wants questa, la, una, etc., before a singular countable noun like malattia.

Yes, there can be.

Both can sometimes translate as serious, but grave often suggests something more severe, dangerous, or medically serious. With illnesses, grave is very common and natural.

For example:

• una malattia grave = a serious/severe illness
• un problema serio = a serious problem

In medical or formal contexts, grave is often the best choice.

Yes. Questa è una malattia grave is grammatical, but it means something slightly different in focus:

• Questa malattia è grave. = This illness is serious.
• Questa è una malattia grave. = This is a serious illness.

The first one directly talks about this illness.
The second one first identifies this as a serious illness.

Both are correct; they just structure the idea differently.