Arrows are used in documents or assignment for variety of purposes, such as, to mark an important point, notes, explanation for a term, listing etc..
In MS Office Word, to create a simple arrow mark we can use ->(hyphen and greater) or => (equal/assignment and greater). To create arrow mark like below in MS-Word,
use, ==>(double equal and a greater symbol) for bold and -->(double hyphen and a greatersymbol) for regular arrow mark