This SQL command creates a new table called 'customer$\_$rental'. It defines the necessary fields with their respective data types and constraints. The 'NOT NULL' constraint ensures that a field must always contain a value. The 'PRIMARY KEY' constraint uniquely identifies each record in the table. The 'FOREIGN KEY' constraint prevents actions that would destroy links between tables. The 'CHECK' constraint ensures that all values in a field satisfy a certain condition, in this case, the check$-$out date must be later than the check$-$in date.