Describe in English a PDA to accept $a^{{?}^{{?}^{?}}}n{b}^{{?}^{{?}^{?}}}m{a}^{{?}^{{?}^{?}}}2,m0$

Write out the state diagram for your PDA

Show the moves of your PDA on some string of length $5$ or more. At each step, be sure to show $($i$)$ state,

$($ii$)$ string left, and $($iii$)$ contents of the stack