VT = virustotal.com, a popular site to check unknown binaries.

C2 = command & control, a server which tells the malware what to do.

C2 is "Command and Control" server I guess. VT no idea.

EDIT: Someone else commented below. VT is number of scans on Virus Total website.

VirusTotal?

VirusTotal, online virus scanner and file sample collection

Command & Control - server coordinating a botnet