"~고 있다" sometimes indicates the result of an action, rather than its progress. This usually happens with verbs such as "입다", "신다", "쓰다", "끼다", which usually mean "wear", "put (on)" etc, and takes "~고 있다" form.
"그 사람은 노란 티셔츠를 입고 있다." is "He is wearing a yellow T-shirt.", "그 사람은 안경을 끼고 있어요." is "He is wearing glasses.", "그 사람은 모자를 쓰고 있습니다." is "He is wearing a hat.", "그 사람은 운동화를 신고 있어." is "He is wearing sneakers."