There are many words and phrases in the English language which have been shortened from the original. This allows ease of use and for quick tying in this digital age. Ed is one of them. It has been shortened from education.
An example of this shortened form in use would be “tech ed”, “phys ed”, or drivers ed, which stands for technical education, physical education, and drivers education, respectively.
The shortened Ed is also used in the name of degree, such as B.Ed. or M.Ed., which stands for Bachelors of Education and Masters of Education, respectively.
In internet slang, E.D. is commonly used to refer to Erectile Dysfunction, a medical condition that affects men.