A data lake is a centralized repository that allows you to store all your structured and unstructured data at any scale. Organizations that successfully generate business value from their data will outperform their peers. More about definition
from AWS here.
In simpler English, a "data lake" is a pool of 100 billion parameters from your normalized data (just like OpenAI did with ChatGPT), as opposed to creating a well-defined dashboard with predetermined APIs.