1.
grass
Plants with narrow leaves growing from the base.
2.
weed
Unwanted plants growing in gardens.
3.
herb
Plants used for medicine or flavoring.
草 means grass, weeds, or herbs - general term for small plants.
COMMON EXPRESSIONS:
- 草を抜く: to pull weeds
- 草むしり: weeding
- 草が生える: grass/weeds grow
COMMON COMPOUNDS:
- 雑草: weed
- 薬草: medicinal herb
- 草原: grassland, prairie
- 草花: flowering plants
- 牧草: pasture grass
INTERNET SLANG:
草 or "w" is internet slang for laughter (like "lol"). Multiple "w" (草草草 or www) = lots of laughing. From the Japanese word 笑う (warau, to laugh).