How Scikit Learn Supports Dimensionality Reduction

As a non-expert in sort of the data science machine learning field, I go in there and I see all these cool algorithms and graphs. But I don't really know like what would I do with that. Maybe we could talk a little bit about some of the algorithms. So for example, it supports dimensionality reduction, like what kind of problems would I bring that in for? It's hard to summarize. The hundreds of pages that you have on scikit learn in the documentation are trying to give you a big picture without too much technical detail.