A fiduciary financial advisor is a financial advisor required to act in the client’s best interest.
There are financial advisors that are not fiduciaries. They are only required to recommend suitable investments, not the best investments. They may put their own interests ahead of their client and sell securities that pay them the largest commission. It's estimated that investors in the U.S. lose 17B USD annually to such actions.
Article from Brilliant Advice
Suitability Vs. Fiduciary Standards