To bake pastry "blind" means to cook it on its own or as an empty tart case, when it will be assembled with or have a filling that will not go in the oven.
Example: "Blind bake the sweetcrust pastry base. "
Meaning: Roll out the sweetcrust pastry to fit the mould or ring, prick all over or cover with ceramic baking beads (or beans/lentils) to keep it flat during cooking, then bake until sufficiently coloured.
Remarks: To read about blind baking in more detail, please see this page.