"Head-on" means "directly". When you deal with a problem "head-on", it means that you do it energetically, and without hesitation.
Here are the common actions that people do "head-on":
face (something) head-on
challenge (someone) head-on
tackle a problem head-on
address (somethiing) head-on
confront (someone) head-on
Doing things "head-on" is almost always positive. Most people agree that problems should be handled "head-on".