Learn Polish: Ten stary mężczyzna tam nie pracuje. - This old man does not work there.

In English, we use helper words like "do" or "does" to make negative sentences. Polish is much simpler! You just put nie directly in front of the verb. So nie pracuje literally means "not works", which translates perfectly to "does not work".

Does nie always have to go right before pracuje?

Yes, for standard sentence negation. When you want to say that an action does not happen, the word nie must sit immediately before the verb it is negating. You cannot split nie and pracuje with other words like tam.

The word mężczyzna ends in "-a". Why does it use the masculine word ten (this) instead of the feminine ta?

Even though most Polish nouns ending in "-a" are feminine, mężczyzna (man) is an exception because it refers to a male person. Its grammatical gender is masculine, so any words describing it must also be masculine, like ten (this) and stary (old).

Could I put tam (there) at the very end of the sentence like we do in English?

Yes, you could say Ten stary mężczyzna nie pracuje tam. Polish word order is flexible. However, putting short adverbs like tam before the verb is very common and sounds highly natural to Polish speakers.