In the middle of the screen, on the left side, there's an exclamation point. Clicking it opens a window with short messages divided into five categories by which they can be filtered: Alerts, Information, Guest Opinions, Help & Tips, Adventurers.
Alerts are messages that require immediate attention. Usually they tell you about things that impede proper functioning of your inn, such as a lack of a resource needed for a dish, mugs, plates, and so on.
Guest Opinions give you updates about how different guests react to your inn. Those can be general (lack of food, bad service) or more precise, like their opinion on a decor of a given room. In the brackets you can see what room they are referring to.
Helps & Tips
These messages show general tips and advice about building and running the inn, such as data on different Social Groups, resource management, and so on.
These messages let you know how well an Adventurer (or another Special Worker) is doing on the Quest they've been sent on (for example: they may be overcoming - or not - obstacles, returning with treasure, etc.)