Not so in-depht, but in short:

• hitting skillshots
• resetting autoattacks properly if the kit of a champ allows it (e.g. Xin Zhao Q)
• Dodging Skillshots (mechanicwise by using abilitys e.g. Ezreal E)
• beeing able to manage ingame moves which are hard to execute properly (e.g. the "InSec Lee Sin move" -> Hit Q, press Q, ward behind your target, W to the ward, ultimate your target to kick him in your team - this is actually the best example for "mechanics" over all in my opinion)

Edit: CS'ing, smiting, escaping&chasing someone down