The function of the part labelled l is to

The part labelled "l" is most likely the female reproductive organ of a flower, known as the pistil. The function of the pistil is to receive pollen grains and facilitate fertilization, resulting in the formation of seeds. The uppermost part of the pistil is called the stigma, which is where the pollen grains land and begin to germinate. The stigma leads down into the style, which is a long tube-like structure that connects the stigma to the ovary. The ovary contains the ovules, which eventually develop into seeds after fertilization. So, the main function of the part labelled "l" is to receive pollen grains and facilitate fertilization, ultimately leading to the production of seeds.