Hii!
MCA stands for Master in Computer Application. In order to join this course in Mumbai University or the colleges under it, you will have to clear the Maharashtra MCA Common Entrance Test. The dates for the exam in the year 2021 have not been released yet. To check for the updates, you can visit the respective official website. The link given below may provide you with more information.

https://www.google.com/amp/s/it.careers360.com/articles/mca-mumbai-university/amp

Hope this helps.
Good luck!