Layer with a filter is a common term for a Vector Layer created with a (advanced) filter to limit the visibility of objects.
Application example:
For the conservationist working in Bielany, we will create a Layer with a filter, containing only the street lights located in Bielany. To do so, we will use the District attribute, which includes the names of the districts.
How to create a layer with a filter?
The answer can be found in the article on creating data (section 4.2.c)
Things to remember when editing layers with a filter
If you create new objects, check if you have filled in the attributes which determine the appearance of an object in a layer, e.g. district=Bielany. Otherwise, you will receive a message: No objects with an identifier… that meets the given condition