what is map([key,] in react code example

Example 1: react map

{array.map((item)=>{
  return (
    <div key={item.id}>I am one Object in the Array {item}</div>
  )
})}

Example 2: map function in react

function NameList() {
	const names = ['Bruce', 'Clark', 'Diana']
    return (
    	<div>
      {names.map(name => <h2>{name}</h2>)}
      	</div>
    )
}