It really depends on your personal skills and wishes, since you literally have a million choices ahead of you, so you need to think carefully. What I could recommend with that amount of money is that you maybe start an affiliate marketing journey, do some dropshipping, or start some blog section from which you will be able to earn later. But, you first have to decide which niche you will select, as no matter which aspect of online business do you choose, this will be one of the most significant steps. Then, after you do that, you can research the market to see where there are some gaps and where you could fit in with your skills.
But don't expect that success will come overnight in any of these aspects, you will need to be consistent and patient, and eventually, you will get those $50 in return, but not immediately, so don't get yourself disappointed if don't monetize quickly, it's completely normal and expected.