Such as an apple tree. In spring the apple tree is covered with flowers. Soon the flower petals fall off and small green balls grow where the flowers were. These balls are little green apples. Bees came to the flowers and pollinated them.
Some fruits have many seeds while others have one.
Let's count and compare the seeds of different fruits. You may use other fruits. Some plants have seeds without flowers such as a pine tree. Wind carries the pollen from the cones and spreads it. Let's think of seeds we eat.