Trojan.Agent refers to a generic Trojan malware detection. It is used for detections that are either associated with no specific malware families or not enough information is available to pinpoint the malware family.
Backdoor.Bot.Gen is the detection for Trojans that allow the threat actor to add the affected system to a botnet. Once this has been established, the machine can also be infected with additional malware.
Malwarebytes can remove these threats without further user intervention.