It's a noun, it means physical, or mental effort.

它是一个名词，意味着体力，或脑力劳动。

Because rearranging limp dahlias into buckets of water requires so much physical and mental effort, doesn't it, Treen?

因为将柔软的大丽花重新排列到水桶中需要大量的体力和脑力，不是吗， 特林？

Conway then made what appeared to be a tremendous physical and mental effort to remember, and said at last that the thing was a Chopin study.

康威似乎费了很大的力气才想起来， 最后说那是肖邦的曲目。