I have a shapefile showing a list of district names. I have (currently in Excel) a long list of district names in a table. I would like to filter those districts that are in the other list. I think this is something to do with the attribute table and an expression, but I don;t know the expression for "this name is another another list".
Try using the 'Join attribute by field value' processing tool
Assuming that both tables have a field in common. I.e. link the two together on district code and then filter your data once joined.