What is this icon on my mac
I don't recognize that, but you can usually figure out any menu bar item by
clicking it or option clicking it. You can usually option drag any Apple item out of the menu bar to remove it:


How can I get rid of this icon in my menu bar?


If not in this specific case, go download this menu bar tool and start digging into what it tells you about that item.


http://www.macbartender.com
Where that icon on my OS X menu bar comes from?


Alternatively, you could isolate this to a user process or system process following this guide:


https://support.apple.com/en-us/HT204772


Once you know if it's a system or user program, you can look at all the places where apps start and figure what software was installed to make that icon. You could save all work and make a system backup and then start killing user processes in Activity Monitor one by one that belong to your user to see which process makes that icon. It's likely not anything from Apple, so simply uninstalling all third party software would be a last resort.