This is the 3547th most frequent Russian word.
сахаром
"Сахаром" is the instrumental case of "сахар," meaning "sugar" (used as "with sugar" or "by sugar").
In this sentence, 'с сахаром' indicates the manner or accompaniment with which the tea is consumed.
Я пью чай с сахаром.
I drink tea with sugar.
Here, 'сахаром' describes the substance used as decoration for the cake.
Торт был украшен сахаром.
The cake was decorated with sugar.
In this example, 'сахаром' indicates the material sprinkled onto the objects during the game.