Backing or support — a person or organization that supports or protects someone (a backer, patron, or sponsor).
彼は大企業を後ろ盾にして事業を拡大した。
He expanded his business with the backing of a large company.
政治家には有力な後ろ盾が必要だと言われることが多い。
It's often said that politicians need powerful backers.
彼女は業界の後ろ盾を得て、プロジェクトを成功させた。
She obtained industry support and made the project successful.
A shield that protects one's back; literally something that guards your rear, often used metaphorically.
戦場で兵士は仲間の盾になり、互いに後ろ盾となった。
On the battlefield, soldiers became shields for one another and protected each other's backs.
会社の内部で彼は重要な後ろ盾を失った。
He lost an important protector within the company.