Umbrella = 雨伞 [yǔ sǎn]
This mushroom’s cap is already shaped like an umbrella, yet in the rain it still holds up a real one over its own head. Rain plus umbrella: 雨伞.
雨伞 (yǔ sǎn) means “umbrella.” 雨 is rain and 伞 is umbrella, so it is literally a “rain umbrella.” In everyday speech people often just say 伞.
Count umbrellas with 把 (bǎ), the measure word for things you hold by a handle: 一把雨伞 (yì bǎ yǔsǎn), one umbrella. To put up an umbrella is 打伞 (dǎ sǎn).
外面下雨了，带一把雨伞吧。 — Wàimiàn xià yǔ le, dài yì bǎ yǔsǎn ba. — It’s raining outside, take an umbrella.
我忘了带雨伞。 — Wǒ wàng le dài yǔsǎn. — I forgot to bring my umbrella.