Буду часа через два, это значит "примерно через два часа" то есть, может раньше а может позже

Thank you! I never could imagine it's meaning by myself.

"Буду через 2 часа" literally means "I'll be there (here) in 2 hours". "Буду часа через два" means "I'll be there (here) in around 2 hours". It's a joke. The gist is that Russian people are usually not very punctual with set time so "часа через два" may often mean anything between 1 and 4 hours.