Meaning:

低调 (dīdiào) low profile; to be modest or to deal with things simply

Usage:

“低调”的本义是指频率低的声调。比喻有能力的人不张扬，保持谦虚的态度；有时也比喻简单处理事情，不引人注意。反义词为“高调”。

The original meaning of “低调”（ dīdiào） is a tone with low frequency. It is a metaphorical description of a capable person, who is always modest and keeping low profile. The antonym of “低调” is “高调”.

Examples:

1. 因为身在国外，没什么亲戚朋友，他们的婚礼办得很低调。

    Yīnwèi shēn zài guówài, méi shénme qīnqī péngyou, tāmen de hūnlǐ bàn de hěn dīdiào.

    They got married with a simple ceremony, for they are aboard and have few relatives or friends here.

2. 刘先生在医学领域取得了很大成就，但是他时刻保持着低调的作风。

    Liú xiānshēng zài yīxué lǐngyù qǔdé le hěn dà chéngjiù, dànshì tā shíkè bǎochí zhe dīdiào de zuòfēng

    Though Mr. Liu has been successful in medical science, he still keeps low key.