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.
Trojan.Glupteba is a backdoor Trojan that enables the threat actor to perform several actions on the affected system. It can download and install further malware and add the affected system to a botnet. It has the tendency to pretend to be an updater for legitimate software.
Trojan.Glupteba is usually dropped by exploit kits.
Malwarebytes can remove Trojan.Glupteba without further user interaction. Be on the lookout for malware that might have been introduced by this Trojan.