在旁边(zài páng biān) - beside, next to in Mandarin

在旁边 (zài pángbiān) means "beside" or "next to". 在 (zài) is "to be at" and 旁边 (pángbiān) is "the side", so together they say something is located at the side of something else, either the side you have just mentioned (银行在旁边 (yínháng zài pángbiān), "the bank is beside it") or a named place tacked on the end (学校旁边 (xuéxiào pángbiān), "beside the school").

The word order trips English speakers up. English puts the preposition first, "beside the school", but Mandarin puts the place first and the position word after: 学校旁边 (xuéxiào pángbiān), literally "school's side". 在 (zài) only appears when you are stating that something IS there, not when you are naming the location itself.

旁边 (pángbiān) on its own, without 在 (zài), is also common and perfectly correct - see the separate 旁边 (pángbiān) entry for that shorter form. This page covers the fuller "is beside / next to" construction with 在 (zài) attached, which is what you will produce when answering "where is it?".