Learn Russian: Бедный студент много работает.

Just like in English, бедный can mean both! It can mean the student literally has no money, or it can be used to express sympathy (like "the poor guy works so much").

Why does бедный end in -ый?

Бедный is an adjective describing студент, which is a masculine noun. In Russian, masculine adjectives usually end in -ый or -ий when they are the subject of the sentence (in the dictionary or nominative form).

Why use много instead of a word like многие?

Here, много is acting as an adverb that modifies the verb работает (works a lot). The word многие means "many" and is an adjective used to describe plural nouns, like "many students".

How do we know if it means "works" or "is working"?

Russian does not have a separate continuous tense (like "is working") in the present. The single word работает can mean both "works" and "is working". You have to figure out which one sounds best in English based on the context.