You can define custom text codes in
UI > Text Codes.
E.g. add one for text code
#test and whenever you use
#test in a text (e.g. of a dialogue) it'll be replaced with whatever content you defined for it.
You can also add overrides for those text codes to game objects in your scenes via
Scene Object components. Those custom text code overrides can either be defined in the component or the settings of the used scene object (or it's type). Scene objects can be set up in
Game > Scene Objects.
The overrides allow you to have different content for the same text code, depending on which NPC is used as speaker of a dialogue. E.g. using a text code
#greeting and have NPC 1 with content 'Hello' and NPC 2 with content 'What's up'.