StringBuffer in Java provides several useful functions to manipulate strings efficiently because it is mutable. The append() method adds text to the end of the existing string, while insert() allows adding characters or strings at a specific position. The delete() and deleteCharAt() methods are used to remove a range of characters or a single character from the string. The reverse() method reverses the content of the string, and length() returns the number of characters present. Finally, the toString() method converts the StringBuffer object into a regular String. These functions make StringBuffer very useful for performing multiple modifications on strings without creating new objects repeatedly.
