Used to express that something is relatable. Similar to 'Same,' but 'Mood' became more common around 2016.

If something is especially relatable, one might say 'Big Mood.' This implies that your whole being is one and the same with whatever you are commenting on.

Intelligence agency term for "psychological operation". A government or corporate-sponsored operation, usually taking the form of a "terrorist attack" or "crazed gunman on a spree", with the intent of panicking the public into demanding more police and laws inhibiting freedom. Psyops are usually carried out by drugging a civilian or group of civilians with aggression-promoting drugs, psyching them up, arming them, and sending them out to commit mayhem. Government-sponsored terrorism. See also blackshirts, conspiracy

Relatable but also summing up your life

When your friend says something relatable and to you, it explains life

Similar to “Same!”, “That is So me!”, or “That’s so relatable!” Mood is used when someone says a phrase or something does and action that you relate to. It is used more commonly nowadays, confusing the older generations.
Sometimes the word big is added to it, to express how much you relate to whatever was said or happened.

can be said in literally any situation

When you can really relate to something someone is saying.