I believe your computer does not have the drivers needed to communicate with the phone. It is like speaking german to an american, you do not understand what they are saying.
First of all, You can search for your phone's drivers via google search. Trust me, i know what the problem is, this also happened to my Nexus 4.
It all should be good from their. If there are still problems, just PM me. Or you can tell me the device name. (ex. Samsung Galaxy Note 2, Nexus 5, OnePlus One, etc.) or if it is a generic phone. tell me.
EDIT: Search ADB Drivers on google. It is a universal driver, and its the one I used with my phone. If this doesn't work, then I don't know what.
Also, I forgot to point out. You have to enable USB DEBUGGING on your phone. If you already have developer options enabled in settings, it should be there. IF YOU DONT HAVE DEVELOPER OPTIONS UNLOCKED, go to settings > About Phone. And tap on the build number 5 times.
IF YOU NOW HAVE DEV. OPTIONS, go to settings > developer options. And click on "Enable USB debugging"
Hope this works.