The paradox goes as follows: there is a heap of sand from which grains are removed one by one. One might construct the argument, using premises, as follows:
1,000,000 grains of sand is a heap of sand. (Premise 1)
A heap of sand minus one grain is still a heap. (Premise 2)
One may object to the second premise by stating that it is not true for all collections of grains that removing one grain from it still makes a heap. The other one may accept the conclusion by insisting that a heap of sand can be composed of just one grain.