I have some money that’s been sitting and cannot decide what to do with it

Okay so I have $40 k in savings as an emergency fund and am adding to that and my 401k a lot right now. I’m wanting to start learning how to grow the money I do have. That being said I have a roll over IRA through fidelity from a job 401k I quit in 2021. That moneys basically just sat there the last 5 years. Give me the nest ways you’d split that between index funds or put it all in one? It looks really easy to trade it on the fidelity app and I can see the major options. It just is a lot of mon