LBJ stands for Lyndon Baines Johnson, a former U.S. president. So the LBJ ranch was one of his personal homes.

LBJ are the initials of Lyndon Baines Johnson, who was vice president of the US beginning in 1961 and then became president when President Kennedy was assassinated in 1963. He was a wealthy Texan (person from the state of Texas) and his family owned a home on a large amount of land used for raising cattle. This land and the house and other buildings on the land are all referred to by the word "ranch." LBJ was born on that ranch and died there. The LBJ ranch us about the size of more than 900 full size soccer fields! (you would call it football, not soccer!)