What to invest Roth IRA in

I’m 22 and I’m I just opened a Roth IRA and an individual account with fidelity. I have a good amount of money saved up and I know if it just sits in a regular bank account it’ll lose value over time. I have $7000 in my Roth IRA and everyone says I should invest in things that track the S&P 500. Should I put all of it into VOO or spread it between multiple index funds?