two grains; two drops; two beads
Counts two small round objects such as grains of rice, drops of liquid, or beads. The counter 粒 (つぶ) is used for small, often round items.
See also: 粒 (つぶ)
I spilled two grains of rice.
I put in two drops of eye drops.
Compound of 二 (ふた, 'two') and 粒 (つぶ, 'grain/drop/bead'). The reading ふたつぶ follows the native Japanese counting system.