What is the funny calculator looking thing on MacBook Pro?

New to Apple and new to MacBook Pro. What is the funny calculator looking thing? It has a drop key, an x<-->y key, a couple of R keys with arrows. Is it valuable? Can it help productivity? Does it allow or discourage user-friendly habits?

Well, it all of a sudden appeared. Replaced a simple calculator with an equal sign. This just has an enter key where "=" would normally be. Earlier today a line started moving across my screen and seemed to be erasing everything in its path. But it seems it might have just been covering characters (words, numbers, etc.) because the characters reappeared. Also I keep getting what appears to be a virus protection ad (seems like MacAfee) obliterating my display telling me I have viruses and telling me to click here. Seems a bit similar to an attack many years ago. I didn't buy the protection for the hp Windows computer - got a different anti-virus program, but I did ask them if they were giving me a virus that only they could fix. I don't know. Is that how is works out there now days?

[Re-Titled by Moderator]