Learn Dutch: De buur helpt mij. - The neighbour is helping me.

Mij is the stressed (emphasized) form, while me is the unstressed form. You use mij here if you want to highlight that the neighbour is helping me specifically (and not someone else). If you are just making a neutral statement, saying De buur helpt me is also perfectly correct and very common in spoken Dutch.

I usually see buurman or buurvrouw for neighbour. Is buur normal to use?

Buur is a correct, gender-neutral word for "neighbour". However, Dutch speakers usually prefer to specify the gender in daily conversation by saying buurman (male neighbour) or buurvrouw (female neighbour). You will mostly see buur in writing, in the plural (buren), or when the person's gender isn't relevant.

Why does the English translation say "is helping" when helpt just means "helps"?

Dutch doesn't have a direct equivalent to the English "-ing" tense that we use to say an action is happening right now. In Dutch, the simple present tense (helpt) is used for both general facts ("The neighbour helps me") and actions happening in the moment ("The neighbour is helping me"). Context tells you which one it is!

Why does helpt end with a -t here?