The corpus callosum is comprised of more than 200 million axons that connect the hemispheres of the brain.

This is true. the corpus callosum connects the right and left hemispheres of the brain with over 200 million nerve fibers or axons

Indeed, the sentence is True.

The corpus callosum is a transverse commissure (means of union between two parts) of the brain present in placental mammals. It is a bundle of axons interconnecting the two cerebral hemispheres. It is the most important commissure of the brain because it connects the four lobes of the brain between them (frontal, temporal, parietal and occipital lobes left and right).

The corpus callosum thus ensures the transfer of information between the two hemispheres and thus their coordination. The other commissures are the fornix, the cingulum and the anterior white commissure.