...
Groups of recipes that belong together are grouped into layers. For example meta-ost is the layer that contains all the things we need in our images. Some repositories are named after layers. They typically contain a collection of associated layers. meta-openembedded is such a collection. It contains various programs split into layers such as meta-connectivity and meta-python. Note that in such cases you need to add each layer in the repository separately (e.g. meta-openembedded/meta-connectivity rather than meta-openembedded). See also: Setting up the Build Environment
Check the Layer page for more information.
...