Bards gain the Countercharm feature at 6th level (emphasis added):
As an action, you can start a performance that lasts until the end of your next turn. During that time, you and any friendly creatures within 30 feet of you have advantage on saving throws against being frightened or charmed. A creature must be able to hear you to gain this benefit. The performance ends early if you are incapacitated or silenced or if you voluntarily end it (no action required).
If the performance has not ended (and I have not voluntarily ended it), am I able to take my movement, action, and bonus action on my next turn? Or do I lose some or all of them?
The performance lasts until the end of my next turn, but it doesn’t state whether or not I am able to take other actions while keeping the performance up.