Hi~
Yes you are right. It has three meanings. One, as you stated, a seafood; abalone.
Second, a verb; roll over - like "A train derailed and turned over" : " 열차가 탈선하여 전복되었다"
Third, a verb; overthrow - "They plotted to overthrow[overturn] the government." :"그들은 정부의 전복을 꾀했다."
If you use Naver, it will help you a lot. It gives the different meanings and examples in korean and english. Best of luck~^^