Using Filament 3 and Laravel 10, if you want to get the label from a select you can use getOptions()
to get an array of the options and use the $state
(or Get works too) to get the value that you selected.
Forms\Components\Select::make('exchange_rate_id')
->relationship('exchange_rate', 'rate')
->searchable()
->preload()
->live() // don't miss this, it's important for this to work