You will most often hear someone say this in the context of something that they are surprised by.
- “That’s a bit much, don’t you think?” they might ask.
In this context, saying that something is a bit much without specifying what it is that is a bit much means that they think someone did something unnecessary. The person they are talking about could have handled their problem in a more reasonable, ethical way. However, they chose to go above and beyond in a way that suggests there must have been another reason for what they did.
For example, a school might find out that a teacher lightly slapped a student in class. This kind of behavior, of course, is unacceptable. The company knows that they must do something to punish the teacher and the other staff involved in the incident. For this reason, they might impose a fine that the teacher and their supervisor(s) have to pay.
Meaning of "Getting on My Nerves" (Idiom)
If this fine is reasonable, you would be able to accept it. However, if this school then sent an email out to all staff about what happened and what the punishment to all those people involved will be, you might think that was unnecessary, and goes over the top. In this case, it would make sense to say that the reaction of the company to what happened was a bit much.
Note that this saying can be used in both the positive or negative ways. The example above was negative. If someone spends 30 hours working on a project that could be done well in 10, for example, that would be a bit much in the opposite way.