Unlike prayer, the question of whether a person fulfills the mitzva of Torah study even if he does not understand what he is saying is more complex.
Similar to the recitation of Shema and the Amida, Torah study also has a component of “you shall inculcate them in your children, and you shall speak of them” (Deut. 6:7), describing the mitzva as orally expressing words of holiness.
This mode of Torah study is typically employed when studying the written Torah.
By contrast, when studying the oral Torah, there exists an additional element, namely, the knowledge of Torah, the understanding and resultant intellectual connection with God’s wisdom.
Thus, one fulfills the mitzva of studying the oral Torah specifically by understanding it. In the. event that he does not comprehend the subject matter, even if it is being verbally expressed, it is not regarded as Torah study whatsoever.
Rabbi Adin Steinsaltz