The most popular one is the money market fund. It invests in T-Bills, Govt Bonds and commercial paper.
These are almost risk free instruments meaning your money is safe.
There are many mutual fund managers in Nigeria today. Make sure to acquire information about interest rates and redemption policies before you invest.
You need N50,000 to open an account. You enjoy the benefits of growing your funds instead of just leaving it in a current account if you have no need for it in the short term