The name Mansfield Park is pretty straightforward – it refers to the main house featured in the novel. The title helps to clue us in to the importance of a certain place and directs our attention to the major setting of the novel, as opposed to just a specific character or a thematic idea, as with some of Jane Austen's other novels. In this case, Mansfield is the epicenter of most of the action. All the major characters have some sort of connection to Mansfield Park, be it through family or through friendships and marriages with the Bertram family, who owns the house.
However, this title isn't just a way to clue us in to the novel's setting. This name also signals one of the novel's major themes: home. The idea of home is really important to lots of the major characters, and home is a concept that's constantly evolving and changing. Mansfield Park itself represents different things to different characters at various times. It's alternately a frightening and alien place, a safe haven, a future goal, a prison, and a place of love. Mansfield Park the house is as complicated as the characters that inhabit it. In fact, Mansfield Park arguably functions as a sort of character itself through the course of the novel.