All strings that contain no run of a’s of length greater than two for $Sigma = {a,b,c}$

The solution to this problem is $(b + c)^*+(b + c)^*((a + aa)(b + c)^+)^*(a + aa)(b + c)^*
$
Isn’t the $+$ sign an union between sets?, I am asking because I am viewing the line $(b + c)^*+(b + c)^*$
as $AUA$ which is $A$ so I do not see a reason to repeat the same set. Thanks in advance.