My advice was over simplified.
In Perl, the various sigils (example: %,$,@) have their own namespaces.

Yes, it is possible to have @x and $x or even %x to be distinct things.
$a is different than @a.

I do not believe that using the same alphanumeric name for a hash, array or scalar is a good idea.
Not everything that is allowed by Perl is "good idea".

I recommend and advise avoiding using "a" or "b" for any kind of user variable.
Consider $a[1] -- that accesses @a instead of the $a scalar. This can be confusing.

I stand by my recommendation to avoid any user variable named "a" or "b" or using the same string to define things like: %xyz, $xyz, @xyz.
Use different names for these very different things.