All data is of a certain type for instance a array of characters, a date, or a number. They can also be an See "Enumerations" which is a custom type with a set range of values.
There is also a wildcard type called Variant. A field or variable of this type can contain anything such as a number or string. Once set however you need to take care when converting a Variant into another type. For instance set a Variant to a string of characters and you would receive an error if trying to convert it into a number (unless the string represents a number)
You can convert from one data type to another under certain conditions. For instance if a String variable contains "123.45" it could be converted to a Float type, however obviously "ABC" could not be converted to a number. Dates can be converted to and from Strings.
The following data types are supported by Flow