What happens when two "INNER JOIN" statements are used in one SQL query?

SELECT Products.ProductID, Products.ProductName, Products.SupplierID, Products.CategoryID, Products.QuantityPerUnit, Products.UnitPrice, Products.UnitsInStock, Products.UnitsOnOrder, Products.ReorderLevel, Categories.CategoryName, Suppliers.CompanyName FROM Products INNER JOINCategories ON Products.CategoryID = Categories.CategoryID INNER JOIN Suppliers ONProducts.SupplierID = Suppliers.SupplierID

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Hi, I'm trying to understanding what is happening in the Northwind database query above. I understand the "SELECT" statement but everything from the "FROM" statement onwards is a bit confusing to me. I was hoping that someone could break it down for me.

Also, shouldn't the Suppliers.SupplierID and Categories.CategoeryID be in the SELECT statement? And Products has a "many to one" relationship with Suppliers and Categories, but what would happen with this statement if the relationship was "one to many"? Would I end up with duplicate Products?