For the sentence: She loves to play the piano in her free time. To identify the part of speech for "loves," its role in the sentence must be analyzed.
A verb signifies an action, state, or event. In this context, "loves" expresses the action or feeling the subject, 'She,' experiences. This action pertains to her affection for playing the piano.
As "loves" denotes 'She's' activity, it functions as a verb.
Consequently, the underlined word "loves" is classified as a verb.