The phrase "bringing close together" refers to the action of moving things or people nearer to each other. This can apply to both physical objects and more abstract concepts, such as ideas or relationships.
When you "bring close together," you are making two or more things less far apart. For example, if you have two chairs across the room, and you move them next to each other, you are bringing them close together.
In a medical context, "bringing close together" can refer to healing tissue, where doctors might need to bring the cut edges of a wound close together to help it heal properly.