The Earth has a diameter of about 12700 kilometers (7900 miles).
The sun has a diameter of about 1.39 million kilometers (865000 miles).
Its diameter is about 109 times the diameter of earth.
The formula for volume of a sphere is V=(4/3) πr3
The approximate volume of the Sun is then 1.3 x 106 times the approximate volume of the Earth.
It would take approximately 1.3 million Earth-sized objects to fill the volume of the Sun.
(*More precise measurements would have to define the surface, i.e. include of exclude the outer layers of the Sun. The Sun is not perfectly spherical and has no "solid" surface.)