You create a magical zone that encourages conversation in a 15-foot-radius sphere centered on a point of your choice within range. Until the spell ends, a creature that enters the spell's area for the first time on a turn or starts its turn there must make a Charisma saving throw. On a failed save, a creature cannot remain silent when asked a question while in the radius. You do not know whether each creature succeeds or fails on its saving throw.

An affected creature is not aware of the spell, and does not know why it is so willing answer questions. However, the creature is not compelled to be truthful, and can be evasive in its answers, or even tell complete lies, as long as it answers the questions put to it.  The affected creature may use audible speech, sign language, writing, gestures, etc. in its replies, but the responses must be obvious to the questioner.

Note that the Zone of Glibness and Zone of Truth spells negate each other.  Whichever spell is cast last cancels the previous spell if their areas of effect overlap.