It currently says:
First accepted answer on your own question.
I find this very confusing since it appears to imply that you can accept an answer on someone else's question, and/or that you can accept more than one.
This is especially a concern since this is probably the easiest badge to acquire and therefore many inexperienced users will run into it.
I think it would be much more clear if we change it to:
Asked a question and accepted an answer.
(Note: I don't think it's necessary to specify that the badge cannot be awarded several times. Usually it's only specified if it can.)