Surface is a line of Windows tablets produces by Microsoft. There are 2 version currently available:
Microsoft Surface RT, which runs on an ARM processor and runs Windows RT by default. Since it runs on an ARM processor, installing Ubuntu on it could be quite complicated.
Microsoft Surface Pro, which run on an Intel i5 processor and runs Windows 8 by default. Installing Ubuntu on this tablet is less complicated since it has an Intel processor.
The Surface doesn't have an optical disk drive, so Ubuntu can be installed either via an Internet connection or via a USB drive.