Here is some useful commands to list the members of a group in Active Directory using PowerShell.
Get members of a group :
Get-ADGroupMember -Identity "Groupe Name"
Get members of a group, recursively (to list all members of sub-groups members of that group) :
Get-ADGroupMember -Identity "Group Name" -Recursive
NOTE : Replace “Group Name” (keeping the double quotes) with the desired Group Name in your AD.