Full form of UKG is Upper Kindergarten.

Upper Kindergarten (UKG) is a preschool or play way school. Kindergarten is a word of German language, which means garden for children. It's educational approach is traditionally based on playing, singing, practical activities such as drawing, and social interaction as part of the transition from home to school. 

These kinds of school or institutions were originally created in the late 18th century in Bavaria and Strasbourg to serve children whose parents both worked out of the home. The term was coined by the German Friedreich Fröbel, whose approach globally influenced early-years education. 

Today, the term is used in many countries to describe a variety of educational institutions and learning spaces for children ranging from 2-7 years of age, based on a variety of teaching methods.