Hypobromite Ion is as follow,
BrO⁻
For Lewis structure, first add all the valence electrons of elements.
So,
Br = 7
O = 6
------------
Total = 13
As there is one negative charge, add 1 electron in total valence electrons,
So,
13
+ 1
----------
14
Now, write both elements and make a single bond between them, and subtract 2 electrons for that single Bond.
Br-O
We are now left with 12 electrons,
Start putting these 12 electrons on both elements so that each get 3 lone pair of electrons with complete octet,
The Final Lewis structure is as follow,