An ETF is sort of a collection of hundreds sometimes even thousands of stocks or bonds in one single fund.
But Mutual Fund is very similar to an ETF but i would say that a Mutual Fund is for beginners and an ETF is for the advanced investors who have been investing for a while. Mutual Fund is sort of an automate version of an ETF.
However If you want a cheaper fees over time and you don’t mind making contributions every month then you should consider an ETF instead of a Mutual Fund.