What do volts and amps imply for angle grinders?
Electric angle grinders are very useful tools, they can also be extremely dangerous. First and foremost, select a tool with as many of the latest safety features as you can afford:


an integral clutch that disengages the drive-line upon wheel bind
a "slow-start" or "soft-start" feature
NO "lock-on" button
a "deadman" trigger or lever feature (shuts off if you let go)
an easily adjustable guard (no tools required)
auto-braking 


Buy gloves, goggles and dust mask when you buy the tool

Amps indicate the power that the motor draws during use and generally indicates the size and power of the motor (higher is "better"). I personally think a well built tool with the features I want and which is comfortable for me to hold and use is more important than the amp rating. If you are routinely grinding and cutting thick heavy hard metal materials you might consider a bigger/more powerful machine. 

Voltage should be whatever your household current is (220-240vt angle grinder would not be practical for home or general shop use, pretty much industrial only)