"дведевочкиисемькошек"

"девочка" is a little girl, like 14 and under, while a young woman is "девушка" (googling both words for images makes it pretty clear).

So, this gets even more disturbing :P

Shouldn't it be одна чашка?

entendí la referencia

Get out of my head! :-)

"Кот" is a (male) cat in nominative singular

"Кошка" is a (female) cat in nominative singular

"Кошек" is (female) cats in genitive plural

Not a native speaker:

Because «девочки» is the genitive singular, which is used with numbers 2-4. «девочек» is the genitive plural and is used with 5 or more, e.g. три девочки, семь девочек.

When you use numbers in Russian, the case of the counted noun depends on the last digit of the number. There's a detailed breakdown here on RussianLessons.net, but basically:

• For numbers ending in 1--but excluding 11--the noun takes the singular version whatever case it would otherwise have. (один will also decline like an adjective. двадцать одна кошка видели меня, "Twenty-one cats saw me", but Я видел двадцать одну кошку, "I saw twenty-one cats.")

• For numbers ending in 2, 3, or 4 (except for 12, 13, and 14), the noun takes the genitive singular, regardless of its role in the sentence.

• For numbers ending 5, 6, 7, 8, 9, 0, and all -надцать numbers (11-19), the noun takes the genitive plural, regardless of its role in the sentence. The "-надцать" rule takes precedence over all others; whether it's 11 or 111 or 1011 or 982350982711, they're all considered to be ending in 11 (одиннадцать), which means they're all -надцать numbers and they all make the nouns they're counting take the genitive plural.

Девочка is feminine. два becomes две for feminine nouns, it just works like that. Like Один becomes одно for neuter and одна for feminine (Similar to Spanish "un gato" vs "una gata").