A hung jury basically just means that the jury cannot agree on whether the person is guilty or not and has to take a longer time to come to a decision.
A hung jury could be that one juror could be undecided on whether the person is guilty or not while the other jurors believe the person is guilty.
If you have someone that is undecided on whether the person is guilty or not then you could have to stay over for the trial on the Jury longer than expected.
Until you all agree on whether the person is guilty or not or if the other Juror doesn't make a decision then you will be on the jury and continue until the person on the jury makes a decision.
It doesn't mean that the person is not guilty or guilty though.
If none of the Jurors can agree or decide on a guilty or non guilty verdict then the defendant will be retried at a later date using another group of Jurors.