Learning new programming languages is an investment in human capital. Thinking about the return on the investment seems therefore natural. Check our blog post on which softwares are most popular among employers in Germany to get started.
The internet is full of data science related online courses. Brendan Martin's comrehensive list on KDnuggets provides an overview of the most popular courses related to data science. Struggling to make a decision which course to take? David Venturi's blog post reviews all available introduction courses and will be a helpful guide in getting started.