A more thorough explanation:

Beneficial owner refers to a person or entity that ultimately owns or controls an interest in a legal entity, such as a security, property, or interest in a trust.

For example, if you own shares in a company through a broker, you are the beneficial owner of those shares, even though the broker is the registered owner. In the securities context, individuals who are beneficial owners of more than 5% of any class of a public company’s stock must file a Schedule 13D or Schedule 13G.

According to Securities Act Rule 13d-3, a beneficial owner is "any person who, directly or indirectly, through any contract, arrangement, understanding, relationship, or otherwise has or shares: (1) Voting power which includes the power to vote, or to direct the voting of, such security; and/or, (2) Investment power which includes the power to dispose, or to direct the disposition of, such security."

For instance, if a person owns 10% of a company's stock and has the power to vote on important decisions, they are considered a beneficial owner. Similarly, if a trust owns a property and a person has the power to make decisions about that property, they are also a beneficial owner.