Would this translate to English as "talking garbage/rubbish"?.Would you use it only amongst friends etc.
The verb "kecat" is a colloquial/slang expression that's only used between friends or in a derogatory sense. Depending on how it's used, it can mean - "to talk nonsense/rubbish", or - it can be used as "Get out!", "No way!" ("Nekecej!" or "Kecáš!") when someone tells you something shocking, or - sometimes it can simply mean "to talk/chat" (e.g. "kecali jsme až do rána" - "we chatted all night").