You can refer to the HKU JUPAS Score Calculator: -
https://admissions.hku.hk/apply/jupas/score-calculator
As long as your DSE Best 6 Scores is over 42 and meet the specific requirements of MBBS, you should have a very good chance to receive an offer.
My son's classmate got a 3 in Chinese and his hallmate got a 4 in English. Both of them got the MBBS offer as their Best 6 Scores are well above 42. Their mediocre language result is not included in the Best 6 Score calculation as they both studied 3 electives + M1/2.