This filter is used to find all the equipment on which a task with the selected tag was created.
Please note that if you select more than one tag, you will see the option "AND" or "OR" next to it.
If you leave the default choice "AND", you will find the equipment that have tasks with all the selected tags (e.g. as in the screenshot below, you will see all the equipment that have at least one task with the tags "machine critique" and "preventif" simultaneously).
If you select the "OR" option, you will find all the results matching at least one of the selected tags (e.g. you will find the equipment that have a task with the "machine critique" tag, but that have not the "preventif" tag, and vice versa).