The Asset Library is a place where you can put entities or assets, and later import them into other scenes.
Importing from the Asset Library
Start by opening the Asset Library dialog by clicking Import Assets in the top menu.
From here you can browse assets by Organization, project and type. It’s also possible to import a file to add it directly to the library.
Choose an asset by clicking it once, and then click the Add button in the right bottom of the dialog window. The asset will be loaded and added to the Asset Bin when it’s ready.
Adding an Asset to the Asset Library
You can not add an Asset directly to the Asset Library. You need to put it in a pack first. More information here.