What is 心血 in English?
一番心血 is a painstaking/ strenuous effort
Examples:
這裡一草一木，一磚一瓦都是我的心血 - Every plant and tree here, every brick and tile here is (the result of) my painstaking effort
嫦娥探月計劃是無數中國人的心血成果 - The Chang'e lunar exploration project is the result of the painstaking effort of countless Chinese people (心血 here is an adjectival noun)
千方百計讓兒子上了醫大，他卻中途退學，枉費了我一番心血- I did everything possible to get my son to go to the University of Medicine, but he dropped out of school halfway through, and it wasted my painstaking effort

endeavor 4. (noun): a strenuous effort; attempt.

You can translate 心血 as painstaking effort, strenuous effort, or endeavor