This is the 500th most frequent Russian word.
тела
The Russian word "тела" means "bodies" (plural form of "тело").
Here, 'тела' is used in the genitive case to denote possession of 'temperature' (of her body).
Температура её тела немного повысилась.
The temperature of her body slightly increased.
In this sentence, 'тела' is again in the genitive plural form, referring to 'bodies' in a general structural sense.
На уроке биологии мы изучали строение тела человека.
In biology class, we studied the structure of the human body.
Here, 'тел' (a related form of 'тело') is in the genitive plural, specifically referring to physical objects as abstract entities in physics.