At the SL, you need to wear a mask entering the establishment. Once you are sitting at a table, you can remove your mask. You don’t need to keep it on while eating or drinking. If you need to use the restroom, order a drink at the bar, go to your room for something, lobby, etc. you get up and put your mask back on. If you are walking around the outside of the tables and bar, you put your mask on. You also wear it when walking out.
You didn’t ask, but a little more info
...before you go in...there is a station to wash your hands (that you must do in order enter)...security then takes your temperature and sprays disinfectant on your hands (I guess they feel that washing them isn’t enough??)...and in you go. Almost every public place has either hand sanitizer or a place to wash your hands before entering. There’s usually also someone there to take your temperature before you enter.