This option lets user include multiple asset definitions into a single otl file without having to worry about uploading each asset individually. The limitation is that only the main asset is visible on Orbolt and all of the dependencies are only usable inside the main asset type. The way this restriction is enforced is by using scoping mechanism in Houdini. The asset dependencies have asset type names prefixed with the main asset type eg. Object/Uberasset::dependentAsset.
Inside the top menu of Houdini, go to: Assets > Other Asset Tools > Embed Internal Assets
If you have an asset with another asset inside of it, and use 'Embed Internal Assets', it will put the internal asset inside the main one, and as a result the operator type will be object/mainasset::internalasset