Every user account is given a 'home directory' to store there personal files, a directory is the same thing as a folder. The home directory is normally named for the users log in name and stored in the /home folder. For example if your account (login) name on the computer is johnsmith, your personal files would be stored in the folder /home/johnsmith. It is not a requirement that home directories be created this way but it is the system default and common convention on many Unix like operating systems.
On PC-BSD a new user receives a set of folders for storing files. Typically these are Documents, Music, and Images. You are free to do any thing you wish within your home directory. Only the root user account and you yourself can modify your files; by default all other users can read files. With the exception of several that are made read-only for security reasons. You can change this, however.