It is disappointed for her fans as they were hoping to watch their favorite player playing in the French Open against opponents. But luck takes it all with it and she has withdrawn herself before 2nd Round match.
During her press conference at Paris today, she said
The injury remains persistent during the US Open of this year, and I was hoping to get fit while joining the French Open, but could not make it. The Achilles’ injury should be taken seriously.Serena Williams Press Conference at French Open Paris 2020
Although she always gives 100% during the match this acute injury prevents her from delivering the best performance.
She is hoping to overcome on injury soon as its not a nagging injury but acute. That might keep her consistent during the early rounds of Roland Garros.
This injury could end her carrier if gotten worse and can cause the rupture of her Achilles tendon or try to ignore symptoms. If it is treated well and on time then she could come back shortly.
WimbledonSport wishes her get well soon.