In the expression 5 + "Five" we have not told the interpreter what to do yet with the value that it has produced, so we need to write a statement to the interpreter in order to execute it. The statement may look like this (for our example): var aString = 5 + "Five". Now the Interpreter understands that we need to concatenate the numerical value 5 with the string value "Five" and assign the resultant value to the variable aString.
An operator is a symbol with an associated known operation to the language. It works on one or more operands. Let's take the addition operator as an example. The + is a symbol, and the associated operation is adding two numerical values like 3 + 9; the numerical values are what we call the operator's operands. We can think of the operands as the values that the operator will work on, like 3 and 9.
The addition operator is called a binary operator because it works on two operands. There are two more categories of operations. The unary operator has only one operand, and the ternary operator has three Operands (we will talk about such operators too). Now let's meet the first family of operators that we will discuss.