To make it even easier, let me just call it STV, single transferable vote, with local designations. They have different candidates. Some of them are from your local area, and they are marked as such. There is a guarantee that at least one of them gets elected. That will make it much easier to understand.
The way things will work is that with mixed member proportional, you vote for your local candidate, who's elected the same way as they are now. Then you will vote regionally, either for a party or for one of the regional candidates. If your local candidate doesn't win, and the party to which the candidate belongs is under-represented, they will use the regional MPs to offset the distortion, to compensate, to make the results proportional. That's mixed member proportional.
The STV, or the local transferable vote that I propose, is one vote, but you rank candidates by preference.