It's a brief, concise definition of what "science" is. However, it doesn't necessarily have anything to say about how science is conducted in the real world.

For example, there's a lot of scientific shenanigans that go on all the time in the pharmaceutical industry surrounding how they go about getting a drug approved for sale. The process may adhere closely to this definition of science even though the actual result--say, a drug that doesn't actually work or a drug that actually causes a lot of harm to people--shouldn't really be possible since everyone was being "scientific" about deciding whether to approve the drug, right? But it happens.

Or scientists are human beings, just like anyone else. There are biases, assumptions, and motivations that can color their judgement and influence their actions just like in any other endeavor even though they are "good" scientists. E.g. what about the hidden problem of topics that scientists avoid researching because they are controversial and could kill their careers or which are not "hot" topics, like say string theory in physics?

Anyway, a definition is nice and all, but it takes a lot more discernment into the whole process and world of "science" to really be critical consumers of it. And just as important as knowing what information to throw out as being being "not scientific" is also noticing what is missing or not being studied and figuring out why that is.