What is translocation in plants? ?

Translocation is the movement of materials from leaves to other tissues throughout the plant. Plants produce carbohydrates (sugars) in their leaves by photosynthesis, but nonphotosynthetic parts of the plant also require carbohydrates and other organic and nonorganic materials.

It's really just sugars and other chemicals produced from a plant and are then transported in the phloem tissue. Assimilates are transported in sieve elements, which work closely together with companion cells to achieve translocation.