As well as the usual gems that need to be matched in rows, Clockmaker features a large number of different mechanics and blockers. To find out or remind yourself what exactly you need to do with any object on the game board, you can open the "Help" section, where you will find information about all the game's mechanics. This section can be found in the game's main menu.
When you tap on the section button, a list of all mechanics opens. When you select a particular mechanic, you will see a short animation that shows you how exactly the mechanic works.
You can use the help section at any time, even when you are playing a level.