Minecraft on multiple devices?

If I have a Mojang account and have Minecraft installed on one device, can I log in from another PC and play the game without any problems?

Not at the same time

Yes, but you can't play from both sides on one server

Yes, that's not a problem at all. You can log in and play on different PCs. However, an account can't be on twice at the same time.

Also note that a Java Microsoft account is not valid for the Pocket Edition or as a console version

What device did you install Minecraft on?