In Polish, both ‘i’ and ‘a’ can be translated as ‘and‘… So which should you use?

i is used when you’re connecting similar things together or describing things which are happening at the same time.

Adam i Ewa mieszkają tutaj

Adam and Eve live here

Matka i córka są z Polski

The mother and daughter are from Poland

Jem i piję

I am eating and drinking

a is used when you’re contrasting things or emphasizing that things will happen at different times.

Matka jest z Polski, a córka jest z Włoch

The mother is from Poland and the daughter is from Italy

Jem, a potem będę pić

I am eating and then I will drink

You might also consider ‘a‘ as meaning ‘and/but‘ or ‘whereas‘ if that makes more sense to you.

One small thing worth noting is that ‘a‘ is always preceded by a comma, whereas ‘i‘ is not.