@RajeshVoleti-4097 The translator essentially counts every unicode code point of input text as a character. Each translation of a text to a language counts as a separate translation, even if the request was made in a single API call translating to multiple languages.
The character and array limits per request is documented here. So, the maximum limit for each translate request is 5K characters and if your request contains 1500 characters to be translated into 3 languages then it results in request size of 4500 characters as observed.
You can also check how a character is counted here.