"Kotu Ellima" is a term in a language called Sinhalese which is spoken in Sri Lanka. It is made up of two words- "Kotu" which means fort and "Ellima" which means five.
So when we say "Kotu Ellima" together, it means five fortresses. Just like how we build sandcastles or forts with five walls to protect it from the waves, a long time ago, people in Sri Lanka built five big fortresses to protect their land from enemies.
These five fortresses were built in different parts of the island, and they were really strong and sturdy, made of stone and surrounded by big walls. Inside the forts, there were houses, temples, and even places where soldiers could stay and protect their land.
Nowadays, these fortresses are popular tourist attractions and they remind us of the history and culture of Sri Lanka. So, "Kotu Ellima" is a phrase that reminds us of the five powerful fortresses that were built a long time ago to protect the land.