Select the latest Media Pack (i.e. Oracle Linux 6 Update 5 (6.5.0) Media Pack).
Now you'll get number of files...
Oracle Linux Release 6 Update 5 Boot iso image - Looks like the barebone minimal ISO.
Oracle Linux Release 6 Update 5 - Looks like it's the basic distro which would solve 90% of peoples need.
And DVD1 and DVD2 are for those who are looking for more apps. Be sure to check if you really need those before you download.