What are some advantages of investing in mutual funds?

Unit Trusts are vehicles to gain exposure to a basket of individual securities. They can both be active or passive investment products. For long-term, buy-and-hold investors who are investing without the need for intra-day trading liquidity, unit trusts can be an efficient product (provided you can keep your costs low!)

As Hariz mentioned, investing in unit trusts at low cost allows investors to access the funds at the actual value of the fund (NAV).

Mutual funds can give you above market returns, or safer market returns.

Your entire sum can be invested instead of when buying ETFs you can only buy whole units and may have extra uninvested monies.

You don't need a buyer to sell your units, you redeem them with the fund house and it's priced by the NAV instead of potential spreads on a stock market.

There are mutual funds that do very specific things or give you access to markets you don't usually have access to.