cursito
short course
curso
course
+
-ito
diminutive suffix
Cursito means short course and can be thought of as a smaller version of curso0 (course0) with the diminutive1 suffix -ito1.
noun
- short courseA short or small course, often used diminutivelyTomé un cursito de fotografía el mes pasado. // I took a short course in photography last month.