Dressing well does not mean having a lot of clothes, it is having the right ones to look better with each of them. There are 7 key clothes that you must have in your closet.
Jacket, sport jacket or blazer. It seems that we are talking about the same garment but they have their differences and it is good to know them to know how to combine.
A blazer is garment for any opportunity, even the one that comes with the suit. You can combine this or others that come separately with any shirt or trouser.