When applying a new law, or researching into some new technologies, you may find that it unlocks new abilities for you to use. Most of these will come from whether you chose to go down the Order or Faith tree in the Book of Laws.
Most abilities will reduce discontent and increase hope, and is especially useful for stopping the Londoners. Pretty much all of the abilities will have cool-downs, usually around a day or two to stop them being too overpowered.
If you are struggling to increase hope and lower discontent, then I recommend using these abilities wherever possible. For example, the Temple offers multiple abilities, such as gathering your workers to pray which will increase hope.

How to activate abilities
To use abilities in Frostpunk, find the building that hosts them. You can usually find out which ones have abilities by looking in the Book of Laws, and looking for the ‘NEW ABILITY:’ text.
In the interface on the right hand side, you can see all of the abilities near the top. On the screenshot above, there are 4 at the temple. You will find a description, the effects and whether it has a cool-down or not.
Just click the ability you wish to activate!