Ummm... You really should understand what you write.
The statement "list p=16F877A" tells the assembler what PIC to assemble the code for. VERY important don't you think, since different PICs have different registers and memory mappings? Ignore it at your peril.
I believe that you could use the processor compiler directive instead, but I also believe that leaving out the list directive will disable production of the listing (*.lst) file, which can be very useful.
By the way... If you have MPLAB installed, start the IDE and go to help. Select the MPASM compiler. It'll explain all of the compiler directives and the instruction set that you may use when creating your programs.
The help is actually pretty well written and useful.