This is something the VA does not advertise very well, just most money for college and education offerings through various other organizations.  VA has a list of certifications that they will reimburse you for, making this virtually a low-to-no cost exercise for you.

Here is the gist of it.  You pass the certification that is on the VA's approved list, send in your receipt from paying for the test and the passing qualification record, and they cut you a check, or if you are already in the VA system for GI Bill, direct deposit the amount into your account.

What is covered?  The cost of the test only.  You are still responsible for the study material and for learning it enough to pass the test.  They do not reimburse a failed test, in case someone is asking that.

Check out the Pamphlet for more information, located here. https://www.gibill.va.gov/pamphlets/LC_brochure.pdf