Two angles facing left, which often indicate, "return to the beginning."
You should methodically test every part of the charging process, including software, the AC adapter, Lightning cable, and Lightning port.
Start by verifying that something is amiss.
You've probably heard the classic advice (immortalized in the British sitcom "The IT Crowd") that the first thing you should try is to turn it off and back on again.
Assuming that your iPad still has some battery life remaining, restart the iPad and then try to charge it again.
Don’t try to charge it via computer