Subject + 变 + 得 + Adjective
变 (biàn) means "to become" or "to change" and is used to describe a shift in state or condition. It can be followed by 得 and a complement to describe how something has changed, or used with adjectives to express that a situation is getting better or worse. It is versatile and appears in both spoken and written Chinese.
天气变冷了,记得多穿点衣服。
Tiānqì biàn lěng le, jìde duō chuān diǎn yīfu.
The weather has turned cold; remember to wear more clothes.
他的中文变得越来越流利了。
Tā de Zhōngwén biàn de yuè lái yuè liúlì le.
His Chinese has become more and more fluent.
城市这几年变化很大,我都认不出来了。
Chéngshì zhè jǐ nián biànhuà hěn dà, wǒ dōu rèn bù chūlái le.
The city has changed a lot in recent years; I can't even recognize it anymore.