Trump is charged with one crime (falsification of records). The penalty for that crime can be elevated to a felony if he committed it while committing or concealing another crime (the "object crime"). The state has thrown out 3 object crimes (federal election violation, state election conspiracy law, and state tax law). The jury has to be unanimous in its verdict on falsification of records. The judge is saying that it doesn't have to be unanimous on which of the object crimes were involved. Whether that is legally correct, I don't know because it is a complicated issue.