Wo youdian kesou (我有点咳嗽。): I have a slight cough

我有点咳嗽。

wǒ yǒudiǎn késou

I'm coughing a little

Character breakdown

I, me

wǒ

to have

yǒu

a little, a bit

diǎn

咳

cough (as in 咳嗽)

ké

嗽

cough (as in 咳嗽)

sòu

The structure is: 我 (I) + 有点 (a bit) + 咳嗽 (cough). 有点 indicates a mild degree, so you're saying you have a slight cough.

我有点儿咳嗽。

wǒ yǒudiǎn er késou

I have a bit of a cough. — Adding 儿 makes it more colloquial and typical of northern Chinese speech.

我有点不舒服。

wǒ yǒudiǎn bù shūfu

I'm a bit uncomfortable. — A more general expression of feeling unwell, not specific to coughing.

我咳嗽。

wǒ késou

I cough. — Shorter and less polite; it sounds more abrupt and lacks the softening effect of 有点.

你怎么了？

nǐ zěnme le?

What's wrong with you?

我有点咳嗽。

wǒ yǒudiǎn késou

I'm coughing a little.

需要去看医生吗？

xūyào qù kàn yīshēng ma?

Do you need to see a doctor?

Appropriate

When you want to tell a doctor or pharmacist that you have a mild cough.
When you want to explain why you are coughing, without making it sound serious.
When you want to politely downplay your symptom, perhaps to avoid worrying others.

Avoid when

When the cough is severe or persistent; then you should use a stronger expression like 我咳嗽得很厉害.
When you are not coughing at all; saying this would be inaccurate. English speakers sometimes mistakenly use 有点 with any symptom, but 有点 implies a mild degree.