Translation:Stay far away from here, do you understand?
some perverse soul seems to have marked us all down for even asking the question/seeking guidance/reassurance from the nice Duolingo community - I can't report the issue until the question comes around again on an exercise but will then do pronto - have marked you nice folks all back up ;)
I feel that have you understood should be accepted but from conversational experience "capito" ie the past participle "understood" is used in a similar way to the English. When being given instructions in Italian it is normal to respond: "ho capito" not "capisco". Hence in this sentence, even though the Italian appears to use past tense, in English we would say "Stay away from here! Understood!" Or more politely: "Stay away from here! Do you understand?"