Indirect addressing means that address of the data is contained in register R0 or R1

e.g.

Mov A,@R0 (while R0=FEH)

will move the contents of location FEH into A.

Note the '@' sign in this indirect addressing mode.

Scratch pad is a general purpose temporary storage. You can use any location of internnal RAM as scratch pad but avoid bit addressable RAM area as it is very useful in some cases.
You will know more as you continue 8051.

Good Luck