¯\_(ツ)_/¯ is a type of emoticon referred to as kaomoji common in Asia (and now worldwide), but like the happy face :-) it is an emoticon (kaomoji use a wider character set than the ASCII commonly used in Western emoticons)

Emoji is a Japanese loan word 絵文字 (literally picture character), you can read more about them:

https://en.wikipedia.org/wiki/Emoji

Emoji in English can used as a singular or plural word but you can also write emojis.