What does she mean by "stick it"?

Native speaker’s answer
Rebecca
By "stick it," she means that gymnasts know how to land in proper form so that they don't get hurt or so that it doesn't look unprofessional. When you see it during a performance, it's like they land perfectly on their feet without any unbalance. Ex: He stuck that landing well. The judges will be happy with that. Ex: Will she stick the landing? That could determine whether she wins or not.