Learn Polish: Studentka z Anglii mieszka w Warszawie. - A student from England lives in Warsaw.

The word studentka is the feminine form. If it were a male student, the word would just be student. In Polish, nouns for people often have different endings depending on their gender.

Why is England written as Anglii instead of Anglia?

The preposition z (when it means "from") requires the following noun to change its ending. This is called the Genitive case. For a feminine country name ending in "-ia" like Anglia, the ending changes to "-ii", making it z Anglii.

Why does the sentence use Warszawie and not Warszawa?

The preposition w meaning "in" requires the noun to be in the Locative case to show where something is happening. For feminine nouns ending in "-a" like Warszawa, the ending changes to "-ie", resulting in w Warszawie.

Why does the verb mieszka not have a pronoun like ona (she) next to it?

Because studentka is already the subject doing the action, so you only need the verb mieszka (lives) to match it. You would use ona if you were replacing the word studentka entirely, such as saying "She lives in Warsaw".