expression
dripping with sweat; by the sweat of one's brow
Idiomatic expression describing hard physical labor or intense effort, often used adverbially with verbs like 働く (work) or 努力する (strive).
彼は汗水たらして家族のために働いた。
He worked dripping with sweat for his family.
汗水たらして貯めたお金で家を買った。
I bought a house with money saved by the sweat of my brow.
汗を流す also means to work hard physically, but it can also refer to sweating from exercise or heat. 汗水たらして emphasizes the visible result of hard labor (dripping sweat) and is more idiomatic.
From 汗 (sweat) + 水 (water) + 垂らして (dripping), literally 'dripping sweat and water'. The phrase is a fixed idiomatic expression.