It is possible to hide meshes, or parts of meshes, using the 'H' hotkey. Use the Paint Mask tool at the top with the Select box tool selected to select polygons or meshes to hide.
You can use 'Ctrl + L' to select the entire mesh after selecting part of it.
To Unhide, you can use 'Alt + H'.
Note that hiding assets is on a mode level (eg. Weight Paint, Edit, etc.) so if you were to go to Edit mode the polygons would be visible again.
In the Paint Mask mode, make sure to select the mesh you want to paint after hiding the polygons. If you have not selected the polygons, you will not be able to paint them.