String, Float, Integer.
String means a word like "Hello" it could me a number added on but it cant be a number on its own. The Float is a number with a decimal like 3.768 but you don't use quotation marks. Finally there's Integer, it's just a number on it's own with no decimals or words just a number like 7.
What is a variable?
A variable is research, mathematics, computer science also it string, float and integer it nearly everything to do with computers.