Filter('Process Details', 'Process Name' = DataCardValue77.Selected.'Process Name').'Process Manager'
Above is the formula written on the item property DataCardValue128 which is a people picker. The value should display from the other SharePoint list page based on the process name.
'Process Name' -> is the column from 'Process Details' SharePoint list
DataCardValue77.Selected.'Process Name' -> is the field where process name is selected.
'Process Manager' -> is the corresponding manager for that process name from the 'Process Details' list
Thanks in Advance