The Resources Panel is the place where you can manage all your Substance Materials which are available on your disk.
There are 3 sections:

• All libraries, where you can find all your assets from Starter assets, Your Assets and linked folders.
• Starter Assets section, where you can find a collection of assets (materials, filters, texture generators).
• Your Assets section is where you can store your assets (images, materials, custo filters, masks, etc.).

For further details, see the dedicated pages:

• Navigating in the Resources Panel
• Creating a local disk folder