SSRS - Display multi-value parameter as text string

=JOIN(Parameters!type.Value,",")

To limit it to a specific length

="Parameter: " +Format(Parameters!DocDate.Value,"dd-MMM-yyyy") +" And Cashier: " +IIF(Len(Join(Parameters!LastUserID.Value,","))>80, Mid(Join(Parameters!LastUserID.Value,","),1,80)+" and more." , Join(Parameters!LastUserID.Value,","))