"Enable recording" or "Monitor" / "Aufnahme aktivieren" oder "Monitor"

Hello guys i am new on Cubase and when i am trying to add some Akkords this pops up “Enable recording” or “Monitor” I would like to know how i can solve this problem, because i couldnt find any sollutions for that. I would be very grateful for help.
Kind regards

Every channel has a record button or a monitor button. Enable it for the track that should play the instrument sounds.