The role and meaning of 'ladder'

The passage below comes from The farewell address of the US President Obama.

https://www.whitehouse.gov/farewell

Our economy doesn’t work as well or grow as fast when a few prosper at the expense of a growing middle class, and ladders for folks who want to get into the middle class.

I'd like to ask the role and meaning of the underlined 'ladders'.
I think it's abverb and seems to mean 'get rid of ladders' in the context.
I know it doesn't make sense grammatically because the subject 'a few' has a plural verb 'prosper' and doesn't agree with the singular verb 'ladders'.
And additionally I cannot find any verb usage for 'ladder' in the dictionary.
But in terms of context I cannot make any alternative better than my answer.

Hope to get your replies.
Regards.