Grass
Grass/Flying weaknesses
Grass/Flying is weak to Ice, Fire, Poison, Flying and Rock, and takes 4× from Ice.
When Grass/Flying Pokémon are hit
4×Hits hardest
2×Super effective
½×Not very effective
¼×Barely scratches it
0×No effect
Its two types separately
Multiply the two to get the result. For example, Ice deals 2× × 2× = 4×.