The taxi stand lets you send guest groups to your own or your friends' resorts. You might want to do that because some of your resorts are tailored to certain types of groups (size or star class wise), or you simply don't have room somewhere but don't want to waste your guests. Of course, you can also just help out friends that need certain guests. You can set which types of guests you want to receive in the taxi stand settings.
The taxi stand doesn't produce anything, and doesn't require staff to run it. All it can do is transfer guests (1 group per slot per day).
You don't need a taxi stand in your other resorts to receive guests, but you do need a taxi stand in any resort from which you want to send guests.
In the beach resort, the taxi stand has a one-time cost of 81,000 HD. This will give you one transfer slot. Additional slots cost 40,500 HD, 81,000 HD, 121,500 HD, 200 Shells, and 203 Shells). Aside from these one-time costs, there are no additional costs for transferring guests. You don't get anything for transferring guests either. The taxi stands for the other resorts are a bit more expensive.