So i have heard about CC a lot and i am new to LoL. I was told it meant "Crowd Control" If this is right what does that actually mean?

to my understanding, it's spells that can slow or stun your enemies.

Its any spell that debuffs an enemy target (slow, fear, stun, snare, etc)

CC means Croud Control, i.e (stuns, slows, snares, silences, etc)

Any spell that can stop a team like
Anivia's Wall.
Ashe's various slows.
Cho Gaths Rapture knock ups.
Ryze stun
Miss Fortunes slow
Morgana's stun

Plus meny meny more

Thanks for the answer. So would Tryndamere's w be a CC cos it slows the enemy and reduces their attack damage for a short period of time.

Tryndamere's W is typically considered a situational CC (you only get the CC, or the slow, in certain effects). The rest of it (the AD reduction) is a debuff.

I don't know if there's a single definition that is agreed upon, so things like Anivia's Wall can be debated; it doesn't directly affect the enemy, but it definitely helps 'control' fights.

Say for instance your team wants to CC (Crowd control) Katarinas ult, you would use something like a warwick or skarner ult that "Suppressed" (Cant be cleansed out of). or stuns work as well, anivias wall however is situational, generally for cutting people off from running into jungle, but if your not careful it can easily backfire and you can trap one of your teammates.

Crowd Control.

Soft Crowd Control manages them, but isn't effective at it. Soft CC is essentially slows of any flavor, and by some definitions silence (how useful a silence is against a target is entirely dependent on what type of character they are).

Hard CC locks down the character, which includes stuns, knock up's, knock backs, suppression, and sometimes silence.

Don't forget blinds. Blinds and silences fall into the same category; devastating against some opponents, but useless against others. (Imagine blinding a mage, or silencing a pure auto attacker.)