This is the 2596th most frequent Korean word.
불확실성
Uncertainty.
In this sentence, "불확실성" (uncertainty) is used to describe the state of his future being unknown and not predictable.
그의 미래는 불확실성으로 가득 차 있다.
His future is filled with uncertainty.
Here, "불확실성" references the unpredictable nature of the economic climate affecting investor decisions.
경제적 불확실성은 투자자들에게 부담이 된다.
Economic uncertainty is a burden for investors.
This sentence uses "불확실성" to explain the speaker's hesitation caused by the lack of predictability in the situation.