Number + 等 + Noun
等 (děng) can function as a classifier or measure word meaning "grade," "class," or "rank." It is used to categorize things into levels or tiers. For example, 三等马 means "third-grade horse" or "horse of the third rank."
这些苹果分为三等,最好的卖得最贵。
zhèxiē píngguǒ fēnwéi sān děng, zuì hǎo de mài de zuì guì.
These apples are divided into three grades; the best ones sell for the highest price.
他的马是一等马,跑得最快。
tā de mǎ shì yī děng mǎ, pǎo de zuì kuài.
His horse is a first-class horse and runs the fastest.
这批货物按质量分成了上中下三等。
zhè pī huòwù àn zhìliàng fēnchéngle shàng zhōng xià sān děng.
This batch of goods was sorted into three grades—upper, middle, and lower—by quality.