"She is eating beef."
Translation:Elle mange du bœuf.
The partitive article is used for unspecified amounts of uncountable nouns. In English, it can translate to "some", but it's often just omitted. Even though English speakers understand this implicitly, in French it is necessary to state that fact overtly, so it is required to use the partitive. Remember that du is a contraction of de + le and that partitives can elide.
See this lesson for a full explanation: https://www.duolingo.com/skill/fr/Food
Can someone explain in which scenario we should use du, i understand du literally meanse some and we should use du where quantity can be measured but in approximation?
You will use "du" to translate the notion of "an unknown quantity of a mass thing" whenever the mass noun is masculine and starts with a consonant sound.
If the noun is masculine but starts with a vowel sound, you will use "de l'".