Netherfield is the name of an estate in Hertfordshire. It is owned by the Bingleys and their arrival was alerted by the Bennets, who live in the Longbourn estate. Mrs. Bennet wishes for her daughters to get married and that's why she sends her daughter Jane out in the rain, where she hopes to get aquainted over there. This would make Jane sick and thus she had to stay in Netherfield for some time, forcing Elizabeth to want to go take care of her sister. Once Jane recovers, Mrs. Bennet lies to her daughters saying their carriage won't pick them up, hoping that if her daughters stay there then they will be with Bingley, "But Mrs. Bennet, who had calculated on her daughters remaining at at Netherfield till the following Tuesday, which would exactly finish Jane's week, could not bring herself to receive them with pleasure before" (Austen. First Edition. pg. 94). But in the end, Mrs. Bennet is much disappointed when they return anyway. Foiling her plans and of course her husband could care less about her thoughts on their daughters.

Austen, Jane. Pride and Prejudice. First Edition. pg. 94. Edited by Robert P. Irvine, Broadview Press, 2002.