This is sold by a marketplace seller. It's says it's a size 10 in women's clothing (as opposed to Juniors or Women's Plus sizes).
Here's all women's swimwear from Sears: sears.com/clothing-women-s-clothing-women-s-swimwear/b-5000960?searsTab=true&excludeMarketplace=true
All women's swimwear from Kmart: kmart.com/clothing-women-s-clothing-women-s-swimwear/b-5000998?kmartTab=true&excludeMarketplace=true
Here's the size guide for women's clothing sold by Sears and Kmart: sears.com/en_us/sizechart/apparel/standard/women/regular0.html
Hope this helps!