Private equity is typically the managing of a portfolio of private investments. It can also be advising private equity companies on buying non-listed companies for investment. Rather than a company issuing shares or debt to a market where it can be openly bought or sold, private equity involves one or more investors taking a "private" equity stake in the firm. This can be from a known investor who may also take part in managing the company.
Since these investments are not "listed" on any stock exchange the realisation or transfer of investment is often when another buyer wishes to purchase the stake or the company is floated or recapitalised.
A typical private equity person will have a broad understanding of capital markets as well as some experience in dealing with corporate and/or institutional clients.