It means Appeal or Dua (Invocation)
A person must make Dua (Invocation) and Seek Allah’s help for any Need and then have faith on His Mercy with patience.
Hadis : From Bukhari Shareef
Volume 8, Book 75, Hadis Number 391: Narrated Jabir (ra)
The Prophet used to teach us the Istikhara for each and every matter as he used to teach us the Suras from the Holy Qur’an. (He used to say), “If anyone of you intends to do something, he should offer a two-Rak’at prayer other than the obligatory prayer, and ” Then he should mention his matter (need).