The icon help tag lets you communicate additional information to your users in an unobtrusive way. It renders as an iconic question mark that provides more information through a pop-up tooltip on mouse over. You can see an example of this in the Control Panel:
<liferay-ui:icon-help/> tag next to the UI that needs tooltip
information. Define the informational text with the required
attribute. Below is an example snippet for one of the Server Administration’s
clean up actions:
<liferay-ui:message key="clean-up-permissions" />
<liferay-ui:icon-help message="clean-up-permissions-help" />
Note that the message is supplied via a language key. While you can use a string for the tooltip’s message for testing purposes, a language key is considered best practice and should be used in production.