You can think of "flink" as being good/clever/skilled at something. It doesn't necessarily have the connotation of being smart or intelligent, because there are many things you can be good at without being particularly bright.
It can also be used in the "good girl" sense, as in "I think you're good because you acted the way I wanted you to".
Generally, I'd say that this is a tricky adjective to translate when there's no preposition involved. When the sentence is "Jenta er (svært) flink [til/i] X" it translates much better.