This study aims to clarify the role of exploiting and practicing mathematical language activities in developing the thinking competence of Grade 10 students in response to the requirements of the 2018 General Education Curriculum. The study employed a qualitative approach through the analysis and synthesis of domestic and international scientific literature, combined with an analysis of typical teaching situations. The findings identified five basic manifestations of mathematical language activities associated with the components of thinking competence and proposed three pedagogical measures: (1) reading comprehension and re-expression of mathematical content; (2) practicing the presentation of logical solutions and transforming representations; and (3) organizing mathematical discussions and debates. The novelty of the study lies in approaching mathematical language activities as a cognitive tool that functions to organize and regulate thinking. The findings contribute to the theoretical foundation and practical orientation for mathematics teaching at the upper secondary school level.