This sentence is an adjective used to describe a person's behavior and appearance. "Gaze" refers to staring at a place, eyes focused and deep, giving people a feeling of deep affection and concentration. "Hooking the lips" refers to the expression that the lips are bent into a certain arc, often smiling, smug or sarcastic. "Smiling" means that the degree of laughter is very light, giving people a gentle and cordial feeling. "A Man in a Painting" vividly depicts the image of this man as elegant and beautiful, just like in a painting, giving people a noble and elegant feeling. Taken together, the whole sentence vividly depicts the image of a beautiful, elegant, gentle and kind person.