Hey ho! What to use on back-end!?

I'll start building my graduation project for college in the near future. It will be a online shop and i need some assistance with choosing stack for it. At fron-end i'll use what i know(React + Redux), but i'm realy bad with back-end. I'm going to build my server with node.js but i don't know what should i use with it(Yes i have heard about frameworks a la express, koa and DBs mongo\postgre and MERN, but what i actually need?).

Someone who has experience with the same case, please tell me a little about it.