How does the Merge Sort algorithm work in the following pseudocode?

Morgosort$($amay $A,$ integor p$,$ intoger $B)$

ther

Margesopt$($A$,$ P$,$ G$)$

$(2)$

Morge$($amay $A,$ integer p$,$ integer o$,$ integer p$)$

n$4$: $q*p+4$

$(1)1+0$

$(2)$

j:: $1$

ropk:

$(2)$

A$|$k$|$: :$||$n$|$

in: :$|+4$

clse

$|A|k|$:$|R||$

H$.$