An informal expression for a person who is troublesome, difficult to deal with, or unreliable; can range from light criticism to exasperation.
職場に困った人がいて、仕事がやりにくい。
There is a troublesome person at work, so it's hard to get things done.
友達の彼は困った人で、約束を守らないことが多い。
My friend's boyfriend is a troublesome person; he often doesn't keep promises.
あの人は本当に困った人だが、放っておけないところもある。
That person is really troublesome, but there are things about them you can't just leave alone.