See, mastering MS Excel takes very little time if you compare it with learning some of the other programming languages, as Excel do not require any coding or programming whatsoever and is completely graphical interface based application.

As far as Python is considered, it is a Programming language and mastering Python may take somewhere between 6 months to an year, depending on how much time you are giving in learning it. Although, it is a very easy language but getting the hang of it is very important, which you can easily do by practicing data structures and algorithms regularly with it.

For learning both, I would suggest you to go with Udemy or Coursera, and for practicing questions, go for Leetcode or Interviewbit as these have a lot of questions and you will be able to master the concepts.

Hope I have answered your question. All the best!