You can manage all sorts of information for individual students. In most cases, you can do this quickly and easily from your "Students" dashboard simply by clicking (or tapping) the 3 small dots at the top right of the student card:
You can add or remove tags for a particular students by selecting or unselecting tags that apply to the student. Dark blue color means the tag is selected, and light grey means the tag is not selected.
Name, email address & picture
You can change the name, email address, or picture of a student by selecting "edit" from the small menu if they are not actively managing their account or profile themselves.

If your student has signed up to Ubindi, they actively manage their own account and profile — so you can no longer edit their personal information. They will have to do that themselves.
Students sign up to Ubindi when they book or reserve one of your classes, or send you a message through the Ubindi email system.
Student notes
You can keep notes about individual students to remind yourself about any special things regarding the particular student. For example, if you are a fitness instructor, you might want to take notes about a students injury or history of physical problems.
To access notes for an individual student, click (or tap) the student name. That will lead to a "student detail page" where you can see everything about the student (including their attendance or purchase history). "Notes" is an editable field for you. Nobody but you can see this.
Assigning a pass