This is the Roman Catholic Church flag. It was adopted by the Holy see on June 7th 1929. It is white and yellow, (gold) with two keys crossed and a Papal Tiara(that thing that looks like crown) inbetween the keys.
The white and yellow represents the albumen of an egg and the yellow (Gold) represents the yoke of an egg. Egg is a symbol of life. Therefore the church stands for life. This is why her mission on earth is the continued nurturing and care for the spiritual life of man in the world through her magisterium and the revealed word of God.
She rejects every form of injury on human life, denoting the preservation of that breath of life which man received from God at creation.
The two keys are those, which Christ handed over to Peter the first Pope. They symbolize The keys of God’s kingdom. One of the key is gold and the other silver in colour. The golden key symbolize the heavenly power which the church commands, while the silver key, denotes the worldly power which she commands.