La dottoressa dice che ho solo un leggero raffreddore.

In Italian, it is very common to use the definite article with professions and titles when referring to a specific person.

So la dottoressa means the doctor or the female doctor.

English often says simply Doctor Smith says... or the doctor says..., but Italian naturally uses the article here:

• La dottoressa dice...
• Il dottore dice...

Dottoressa is the feminine form, so it is used for a female doctor.

• il dottore = a male doctor
• la dottoressa = a female doctor

In Italy, dottore/dottoressa is also a very common way to address or refer to doctors.

Che introduces the second clause and means that here.

• La dottoressa dice che... = The doctor says that...

It connects dice with what is being said.

In English, that is often optional:

• The doctor says that I only have...
• The doctor says I only have...

In Italian, che is normally kept.

Because Italian expresses this idea with avere (to have), just like English does in I have a cold.

• ho un raffreddore = I have a cold

You do not say sono un raffreddore.

There is also another Italian expression:

• sono raffreddato / raffreddata = I have a cold / I’m suffering from a cold

But in your sentence, the structure is:

• ho + un raffreddore

Italian often leaves out subject pronouns because the verb ending already shows who the subject is.

• ho = I have
• hai = you have
• ha = he/she has

So ho already tells you the subject is I, and io is unnecessary unless you want emphasis or contrast.

For example:

• Io ho un raffreddore, non lui. = I have a cold, not him.

Solo means only or just.

In this sentence, it limits the whole noun phrase un leggero raffreddore:

• ho solo un leggero raffreddore = I only have a slight cold

The idea is that the illness is not serious — it is just a mild cold.

Its position is natural here because it comes right before the thing being limited.

Both adjective positions exist in Italian, but they are not always equally natural.

Here, leggero before the noun sounds very natural and idiomatic:

• un leggero raffreddore = a slight/mild cold

With many common descriptive adjectives, putting the adjective before the noun can sound more fixed, flowing, or general in tone.

If you said un raffreddore leggero, it would still be understandable, but it sounds less natural in this context.

Raffreddore means a cold, as in the common illness.

So:

• avere il raffreddore = to have a cold
• un raffreddore = a cold

Be careful not to confuse it with:

• freddo = cold as temperature
• raffreddore = cold as illness

So ho freddo means I am cold, but ho un raffreddore means I have a cold.

Because raffreddore is a singular masculine countable noun, so it takes the indefinite article un.

• un raffreddore = a cold

Since leggero is just the adjective describing raffreddore, the article still agrees with the noun:

• un leggero raffreddore

A couple of useful pronunciation points:

• che is pronounced like keh, with a hard k sound.
• ho is pronounced simply like o. The h is silent.

That silent h in forms of avere is there for spelling reasons:

• ho = I have
• hai = you have
• ha = he/she has
• hanno = they have

It helps distinguish them from other words like:

• o = or
• ai = to the
• a = to
• anno = year

Usually no, not in a normal sentence like this.

English can say:

• The doctor says that I only have a slight cold
• The doctor says I only have a slight cold

But Italian normally keeps che:

• La dottoressa dice che ho solo un leggero raffreddore.

Leaving it out would sound wrong or very unnatural here.