Answer by taking a quote from the following article:

Stanley Kirk Burrell (born March 30, 1962), better known by his stage name MC Hammer (or simply Hammer), is an American hip hop recording artist, dancer, record producer and entrepreneur. He had his greatest commercial success and popularity from the late 1980s, until the early 1990s. Remembered for his rapid rise to fame, Hammer is known for hit records (such as "U Can't Touch This" and "2 Legit 2 Quit"), flashy dance movements, choreography and eponymous Hammer pants. A multi-award winner, M.C. Hammer is considered a "forefather/pioneer" and innovator of pop rap (incorporating elements of freestyle music), and is the first hip hop artist to achieve diamond status for an album.

Before Hammer's successful music career (with his mainstream popularity lasting approximately between 1988 and 1998) and his "rags-to-riches-to-rags-and-back saga", Burrell formed a Christian rap music group with CCM's Jon Gibson (or "J.G.") called Holy Ghost Boys. Some songs produced were called "Word" and "B-Boy Chill". "The Wall", featuring Burrell (it was originally within the lyrics of this song he first identified himself as K.B. and then eventually M.C. Hammer once it was produced), was later released on Gibson's album Change of Heart (1988). This was Contemporary Christian music's first rap hit ever. Burrell also produced "Son of the King" at that time, releasing it on his debut album. "Son of the King" showed up on Hammer's debut album Feel My Power (1987), as well as the re-released version Let's Get It Started (1988).  With exception to later remixes of early releases, Hammer produced and recorded many rap songs that were never made public, yet are now available on the Internet. Via his record labels such as Bust It Records, Oaktown Records and FullBlast, Hammer has introduced, signed and produced new talent including Oaktown's 3.5.7, Ho Frat Hoo!, the vocal quintet Special Generation, Analise, James Greer, One Cause One Effect, B Angie B, The Stooge Playaz, DASIT (as seen on ego trip's The (White) Rapper Show), Teabag, Common Unity, Geeman and Pleasure Ellis; both collaborating with him and producing music of their own during his career.  At about the age of 12, Oakland native Keyshia Cole recorded with Hammer and sought career advice from him.

What did he do in entertainment other than music?
At about the age of 12, Oakland native Keyshia Cole recorded with Hammer and sought career advice from him.