Translation:Please wait here.
For a short answer: yes and no. It's actually acceptable to say "请这里等", but if you put the 在 it gives the sentence more stress. So you kind of give the "这里" (which means 'here') to be the center of attention of the sentence; while saying it without 在 will make the sentence less understandable for some. Yes, few words in Chinese are just to stress the sentence a bit, like maybe you've seen 了，呢，including this 在. You'll get it over time!!
*Please correct me if I'm wrong.