its called a computer bro, or graphics card if you want to get technical.
The reason its not working when you plug it in to your tv(when your not in safe mode) is because its not able to handle the resolution your computers set to.
So right click on a blank spot on your desktop, pick the settings tab, and on the section "screen resolution", move that slider down 1 time and click apply, if it still doesnt work move the slider down again/click apply, and repeat till its working