Simplify the following text for a Grade 10 native English-speaking person.
Original: Akiba Kiwelowicz Rubinstein ( 12 December 1882 , in Stawiski , Poland â `` 15 March 1961 in Antwerp , Belgium ) was a famous Polish chess Grandmaster at the beginning of the 20th century .
Simplified: Akiba Rubinstein ( Stawiski , Poland , 12 December 1882 â `` 15 March 1961 , Antwerp , Belgium ) was a Polish chess Grandmaster in the first part of the 20th century .