Explain like I only speak in plain English

Foo, bar, and baz are used as placeholders when giving examples in programming. It's like placeholder names that refer to objects or people when telling a story. Such as "widget" or "John Doe". The actual names are irrelevant and do not affect the message being conveyed.

Programmers usually start with foo if only one placeholder name is needed. Then they will use bar, and finally baz. If more are needed, there is qux, quux, quuz, corge, grault, garply, waldo, fred, plugh, xyzzy, and thud.

Explain like I'm a total nerd

In Python, spam, ham, and eggs are used instead. It is heavily influenced by the creator's love for British comedy show Monty Python.

Foo, bar, and baz are generally called metasyntactic variables. It stems from mathematics where algebra letters such as x, y, c, are used in place of numbers.

Foo, bar, baz are more generally referred to as just foo bar. They are probably as legendary as "Hello World!" in computer science.

Explain like I'm an artist

Foo, bar, baz, is like "lorem ipsum" in publishing and graphic design. They are used as placeholder text to demonstrate a programming example where names are not important.

Explain like I already know it

A foo walks into a bar, takes a look around and says: "Hello world!". Hahahahaha. Good one.

Programming

Programming is creating instructions for the computer to perform specific tasks. A person who writes programs is called a programmer. There are many different programming languages a programmer can write programs in.

Variable

A variable is a temporary storage unit in a program. You can think of it as a box. You can use this box to hold an item. You can retrieve the item stored, or swap it with another item.

Function

A function can be thought of as a machine that performs a specific task. Such as make sandwich. Every time you want a sandwich to be made, you just have to turn on the machine. Or execute the function, as programmers would say.