The adessive case is like a special outfit that some words can wear to show where they are located. It helps us understand where things are in relation to other things.
Imagine you have a toy car and you want to say that it is on the table. The word "table" would wear the adessive case so it becomes "table-on" which means "on the table".
Another example would be if you want to say that you are at the store. The word "store" would wear the adessive case so it becomes "store-at" which means "at the store".
This special outfit can only be worn by certain words like nouns and pronouns that are usually the subject of a sentence. They change their form slightly to show their location.
In summary, the adessive case is like a GPS system for words. It helps us understand where things are in relation to other things.