Certain school boards require homestays that host their students to satisfy some additional requirements to be approved. Homestays that are located in cities governed by those school boards will be awarded a badge if they satisfy the requirements by the school boards.
You may find a list of School Board Badges that Homadorma collaborated here: School Board Badges
Note: Homestays without School Board Badges are not necessarily bad. It is possible that they are not located in the cities of governance.