HYIPS is an acronym (abbreviated phrase) for the term High Yield Investment Program.
A "high yield investment program" refers to investments where you can earn high interest, build capital gain, collect rent or other forms of revenue etc,. which provide a high rate of return (or yield).
Typically, promises of high yield also come with a higher level of risk. It is usually recommended to seek financial advice from a professional and make sure you have a balanced portfolio (a mix or low and high risk investments).