This is the 11166th most frequent Russian word.
грамма
The Russian word "грамма" means "gram," a unit of mass.
The word 'граммов' is the genitive plural form of 'грамм' (gram), used to indicate the amount of milk bought in grams.
Я купил сто граммов молока.
I bought one hundred grams of milk.
The word 'грамма' is the genitive singular form, used in a negative context to indicate a complete absence of sugar.
У меня нет ни грамма сахара.
I don't have a single gram of sugar.
Here, 'граммов' is again the genitive plural form, used to request a specific amount of tea to be weighed.