rate; ratio; proportion (used to indicate the share or proportion of something).
合格者は全体の3割だった。
Those who passed made up 30% of the total.
外国人の割合（＝外国人の割）は年々増えている。
The proportion of foreigners has been increasing year by year.
この年代で英語が話せる人の割はいくらですか？
What proportion of people in this age group can speak English?
one tenth; ten percent (the unit 'wari' where 1 wari = 10%).
給料が2割増えた。
Salary increased by 20% (two tenths).
商品の値段が1割引になった。
The product's price was reduced by 10%.
(comparative) profit or worth; used in expressions like 'worth it' (割に合う) or 'not worth it' (割に合わない).
この仕事は時給が低く、割に合わないと感じる。
I feel this job isn't worth it because the hourly pay is low.
労力の割には成果が少なかった。
The results were small compared to the effort put in.
assignment; allotment; allocation (used when distributing people or resources).
予算の割り当ては明日決める予定だ。
The allocation of the budget will be decided tomorrow.
チームごとの仕事の割り振りを行った。
We assigned tasks for each team.
sumo-specific term: a match list or schedule of bouts (e.g., 'torikumi-wari').
今場所の取り組み割が公式サイトで発表された。
The bout schedule for this tournament was announced on the official site.
diluted with (of drinks); mixed with water or another mixer (as a suffix, e.g., 'mizuwari' = whisky with water).
ウイスキーの水割りをください。
I'd like a whisky with water, please.
ジュース割りにすると飲みやすくなる。
If you mix it with juice it becomes easier to drink.
discount; rebate (abbreviated use indicating the rate of discount).
今日は全品二割引です。
Today everything is 20% off.
会員はさらに1割引が適用される。
Members get an additional 10% discount.