The spelling שמן can represent both a noun (pronounced /ˈʃe.men/ (shémen), meaning “fat” as in grease or cooking oil) and an adjective (pronounced /ʃaˈmen/ (shamén), meaning “fat” both as in the sense of overweight and of greasy). The image, the translation and the category point to the latter but the pronunciation is of the former.
In the same skill there is also רזה meaning “thin”. The masculine and feminine singular forms of the adjective are spelt the same but pronounced differently (masculine /raˈze/ (razé), feminine /raˈza/ (razá)). The audio uses the feminine form, which isn’t technically wrong and in itself wouldn’t be a problem if it were transparent for the learner and consistent with other adjectives (e.g. שמן whose feminine form would be שמנה, pronounced /ʃmeˈna/ (shmená)).