"Mom makes juice."
Translation:Мама делает сок.
Be careful! «Сока» is not in the nominative form. The nominative form is «сок», and since it’s a non-animate masculine noun in the singular form (complicated but essential to know) it will remain «сок» in the nominative form; therefore, it is: «Мама делает сок». «Соку», the word you’ve mentioned, isn’t an incorrect word, but it’s in the dative form, and you’ll know more about that in further lessons.
Genitive ‧ From Renaissance Latin casus genitīvus, literally "case pertaining to origin, birth", from genitus the perfect passive participle of gignō (“beget”). ‧ (grammar) Of or pertaining to that case (as the second case of Latin and Greek nouns) which expresses a quality, origin or possession. It corresponds to the possessive case in English. ‧ en.wiktionary.org/wiki/genitive ‧
Genitive case signals a relationship of possession or “belonging to ‧ courses.dcs.wisc.edu/wp/readinggerman/genitive-dative-cases/ ‧
‧ Nominal declension involves six cases – nominative, genitive, dative, accusative, instrumental, and prepositional ‧ en.wikipedia.org/wiki/Russian_grammar ‧
де́лать ‧ Transitive ‧ en.wiktionary.org/wiki/делать ‧
Мама ‧ делает ‧ сок.
Subject ‧ T Verb ‧ DO
Мама ‧ Subject
делает ‧ Transitive Verb
сок ‧ Direct Object - Accusative Case
An intransitive verb cannot take a direct object by definition. ‧ www.russianforeveryone.com/Rufe/Lessons/Course1/Grammar/.../GramUnit9_1.htm ‧
Accusative case. The accusative case (abbreviated acc) of a noun is the grammatical case used to mark the direct object of a transitive verb. ‧ en.wikipedia.org/wiki/Accusative_case
‧ Accusative Case - Direct Object ‧ Whenever a verb, like "read", "cut" or "want" acts directly on some noun, the latter is a Direct Object. Such Nouns take the Accusative case. ‧ ‧ www.duolingo.com/skill/ru/Accusative-Case:-the-direct-object/tips-and-notes ‧