投资(tóu zī) - to invest, investment in Mandarin

投资 (tóu zī) covers both halves of the English pair: the act of investing and the investment itself. As a verb it takes the money-holder as subject, 他投资了很多钱; as a noun it counts with 笔, so 一笔投资 is one investment.

Word order is where learners slip. English says invest in something, and Mandarin has two ways of doing it. Either name the target directly, 投资一家公司, or bracket it with 把 and 在 as in 把钱投资在教育上. What you cannot do is graft the English preposition on and say 投资在一家公司 without the 把 clause holding the money.

The figurative use travels well. Time, effort and study can all be 投资, and 对自己的投资 is a perfectly ordinary phrase. Note that the second character is 资 (zī), the capital in 工资 wages and 资料 materials, not 姿 or 咨, all three of which sound identical.