@vivekktr To know what an enumerable is, you must understand the verb/action enumerate. The definition of enumerate is: “mention (a number of things) one by one.”
An enumerable is just a read-only object that you can enumerate over. This means it is a collection of any type of variables that you can go through one-by-one. Since it is read-only, you can’t change the enumerable itself, you just read the information from it. This makes it the least resource intensive type of collection to iterate through (vs list, array, etc.)