I find Wikipedia a useful source of information. Here is the Wikipedia explanation.
A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely.
The earliest programming languages predate the invention of the computer, and were used to direct the behavior of machines such as Jacquard looms and player pianos. Thousands of different programming languages have been created, mainly in the computer field, with many more being created every year. Most programming languages describe computation in an imperative style, i.e., as a sequence of commands, although some languages, such as those that support functional programming or logic programming, use alternative forms of description.
A programming language is usually split into the two components of syntax (form) and semantics (meaning). Some languages are defined by a specification document (for example, the C programming language is specified by an ISO Standard), while other languages, such as Perl, have a dominant implementation that is used as a reference.
If you invent a ‘Toaster’ and wanted to program the same think of the syntax and semantics you could use.
Select – Choose Type of Bread
Pre Warm [period] – duration of pre-warm time
…. Similarly for toasting and cool down tim
…. Add a variety of alarms etc.
…. Test Moisture Level etc.
Hopefully you get the idea..