Here is a photograph of an array of lego minifigs. In computer programming, most languages would say that the array depicted would be [15] as the first minifig would take up position 0 and the 2nd would have position 1 and so forth.
Variables exist everywhere in our life. It does not need to be unknown. Take for example these scripts from the computer program Scratch. The variables identified are events. For example a variable for you might be when you get breakfast. The variable could be when at what time do you feel hungry, or what you have for breakfast.