I cannot understand function argument variables like what is argument and variable

Question

for e.g
def something (variable)
print variable+=1. =8
I cannot understand it what is it how it answers 8

Answer 1

because variable is assigned to 8 always

Answer 2

whats that mean assigned

Answer 3

the statement is like

variable =variable + 1 =8

here variable+1 and variable = 8 always than ans is 8

Answer 4

why is it 8 plz define