You're going to have to read up on assembler syntax for that. Basically, the entry.s is the first thing executed and calls a C function. The blobs.s file includes binary files (INCBIN) between two labels which are used to calculate (when linking the final thing) the proper offset and filesize required to copy the program into camera memory.
You'll want to search for ARM document DUI0068, it's a nice thing to get started with ASM. As for the '.-notation', I didn't really see that covered in that document (I may be wrong) so I can't help you with that. I don't know how I learned the meaning of those directives but I just do, when I see them.