Here you can define you user variables.
Set
variable: Creates a normal user variable. This will always be lower case and spaces are not allowed.
static: This is a static that can not be populated dynamically in workflows.
as
string: Sets the variable/static as a text string. This is default
integer: Sets the variable/static as an integer; whole number.
float: Sets the variable/static as floating point number.
Description/Content
When "variable" is selected, this option will read "Description". Here you can just write a description for the variable and its usage.
When "static" is selected, this option will read "Content". Here you set the content of the static. This can be a long path, a name that might change some time or some other data. This is a bit like setting a global Windows environment variable.