Poster, Playbill, Lawn Sign
This is a white placard with a brown wooden stick, which can be seen on the roadside or in the park, for example, it reads a reminder: "Do not pick flowers". In addition, you may see it in some protest occasions, some people hold placards with some protest words written on them.
This emoji is usually used to express tips, promote ideas, business or commercial advertisements, and can also be used in protest-related content.