name is a String object.
String class has the [] instance method that let you
extract parts of the String object.
In this case name[0] returnes the first character of name
name[1..-1] will give back a new string without the first character
https://ruby-doc.org/core-2.7.2/String.html#method-i-5B-5D

You misunderstood the task. You need to find the outlier, which can be odd OR even. You should read the description again.

Read this: https://github.com/codewars/codewars.com/wiki/Troubleshooting-your-solution#post-discourse

return the length of the shortest word(s).

Not the shortest word.

#<TypeError: no implicit conversion from nil to integer>

It fails for [].

Not a suggestion, rather a question. RETURN the result (as the name implies), not print it (this applies to all katas).