Number + 节 + Noun
节 (jié) is a measure word (classifier) used for segments, sections, or joints. It is commonly used to count vertebrae, class periods, train carriages, batteries, and other items that are part of a segmented whole.
今天下午有两节数学课。
Jīntiān xiàwǔ yǒu liǎng jié shùxué kè.
There are two math classes this afternoon.
这列火车一共有十六节车厢。
Zhè liè huǒchē yīgòng yǒu shíliù jié chēxiāng.
This train has a total of sixteen carriages.
遥控器里要装两节电池。
Yáokòngqì lǐ yào zhuāng liǎng jié diànchí.
The remote control needs two batteries.