Noel’s answer is correct. I would add that the expression comes from card games (like poker) in the gambling world. You hold your playing cards close to the chest/vest to be sure that nobody else can see what cards you have.
2017년 11월 4일
0
4
2
Close to the chest (or close to the vest) means to be cautious when dealing with the outside and giving nothing much or nothing at all away as far as future plans, trade secrets, etc.
Hope this helps!