A Play is whenever someone hits the play button on your track, but a Listen is only if they listen for more than 10 seconds.
For votes you'll see 2 different numbers. The first is Indaba votes which is votes from other Indaba users and is currently used to calculate the leader board. The second is Facebook votes which anyone can do by connecting their facebook account to Indaba.
Often friends of contestants will say they voted because they clicked the 'Vote' button, but if they didn't fill in their Facebook info when prompted to no vote will be recorded.
Please also note that the leader board is not calculated in realtime so their may be some discrepancies between it and your track but if given a little time it will update.