Instead you have what is known as a scalar variable. Scalars can contain all types of data. Floats, Strings, Integers, etc to name a few. Although their variable names stay constant throughout the program, a variable may contain an Integer at one point and then a String at another. For this reason it is VERY important to comment Perl scripts well, because can occasionally get a bit confusing.
Scalars begin with a dollar sign and then the variable name.
After that you may choose whether to use letters, numbers, or underscores. You may want to also keep track of your variable types. One popular method is known as Hungarian Notation. What this means is that you start every variable with one or two lowercase characters describing its type. Using Hungarian Notation will greatly help you in debugging your code by allowing you to distinguish different variable types.