Find the the date of enrollment of the "Spanish" course.
SELECT T2.date_of_enrolment FROM Courses AS T1 JOIN Student_Course_Enrolment AS T2 ON T1.course_id  =  T2.course_id WHERE T1.course_name  =  "Spanish"
date of enrollment refers to date_of_enrolment; 'Spanish' course relates to filtering by course_name = 'Spanish'; joining Courses and Student_Course_Enrolment tables on course_id to find related data;