Application redirects me to mainURL/assets

it's my .htaccess file. When I put manURL to browser it takes me mainURL/assets/ and shows 403 error. Here I need to select language like mainURL/bn or mainURL/en.

<IfModule mod_rewrite.c>
        <IfModule mod_negotiation.c>
            Options -MultiViews
        </IfModule>

        RewriteEngine On

        # Redirect Trailing Slashes If Not A Folder...
        RewriteCond %{REQUEST_FILENAME} !-d
        RewriteRule ^(.*)/$ /$1 [L,R=301]

        # Handle Front Controller...
        RewriteCond %{REQUEST_FILENAME} !-d
        RewriteCond %{REQUEST_FILENAME} !-f
        RewriteRule ^ index.php [L]

        # Handle Authorization Header
            RewriteCond %{HTTP:Authorization} .
            RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
</IfModule>

via Md. Habibur Rahman