I am not sure what do you talk about, i assume it is a type of the numeric variables.
There integers where there is no decimal point.
There are decimal numbers, they have integer part and fraction part and between them there is the decimal point.
Here are two subtypes, the first has fixed number of decimal numbers, and the second part where the decimal point can move left-right or foreward-backward.
Here is the web page what is describe this variable type, better than me:
Floating point