Equities are a very common way of investing that involves buying shares in a company and sharing in that company’s profit (owning a piece of the company, basically). As companies make more (or less) profit over time, other people might want to buy the shares from you, so you also make money if you sell those shares for more than you bought them for.
Historically, investing in equities has meant your money grew much more over the long-term than investing in other ways, although there can be ups and downs along the way. Most pension plans are made up of a mix of equities, bonds and other investments.