This is too general, like what. What do you want to do. Almost anything can be defined in a .profile.
What would you like to do.
You can change the prompt. You can alter the $PATH variable, add alias commands for common commands with options that you type. ex. alias dir="ls -lrt". For root user .profile, you can trap user commands that su to root as separate files by userID.
There is the system default file /etc/profile or the one that is used to create new users in /etc/skel/.profile
Please expound on your question.