Understanding WCAG2.0

If the label is insufficient to explain all functions, it is desirable to provide help separately. Even if you write a description near the form, it is considered as help in 3.3.5.

Principle Understandable Information and the operation of user interface must be understandable.
Guideline Input Assistance Help users avoid and correct mistakes.
Criterion Help
(3.3.5 AAA)
You can use context-sensitive help.

URL of Techniques for WCAG 2.0