This is the 2682nd most frequent Japanese word.
減らし
"Reduction" or "decrease."
The verb '減らす' is conjugated to '減らしました' in its past tense form, which means 'reduced' or 'decreased' here.
私は食べる量を減らしました。
I reduced the amount I eat.
The word '減らす' in this sentence is in its dictionary form, referring to the concept of reducing or decreasing something—'to reduce' garbage.
ゴミを減らす方法を考えています。
I am thinking of ways to reduce garbage.
The phrase '減らしましょう' uses '減らす' in its volitional form, showing intention or encouragement to reduce waste.