what is the use of function expression in javascript code example

Example 1: js function expression

const plantNeedsWater = function(day){
  if (day === 'Wednesday'){
    return true;
  } else{
    return false;
  }
}

console.log(plantNeedsWater('Tuesday'))

Example 2: javascript function expression

const mul = function(x, y){
    return x * y;
}; //semicolon needs to be there as it is expression

console.log(mul(10, 20));