As a ribosome translocates along an mrna molecule by one codon, what happens after it?

The tRNA is released from the E site of the ribosome and the elongation process finishes while the termination process starts.

Explanation:

When the translocation process is finished the tRNA that is in the E site of the ribosome is released and the A site of the ribosome reads a stop codon in the mRNA in order to finish the elongation process and start with the termination process. In the termination process a termination factor joins the stop codon, the ribosomal subunits split apart, the protein and the tRNA dissociate from one another and the tARN is not in the P site of the ribosome anymore.