If you have an account and don't want to leave the article to find out the class, you could enable the metadata gadget. [2]
[1] https://en.wikipedia.org/wiki/Talk:Charles_Dickens [2] https://en.wikipedia.org/wiki/Wikipedia:Metadata_gadget
For example,
https://en.wikipedia.org/wiki/Talk:Charles_Dickens
You'll see:
--- This article is of interest to the following WikiProjects:
* WikiProject Biography / Arts and Entertainment (Rated B-class)
* WikiProject England (Rated B-class, Top-importance)
* WikiProject Children's literature (Rated B-class, Top-importance)
* WikiProject Hampshire (Rated B-class, Top-importance)
* WikiProject Journalism (Rated B-class, High-importance)
* WikiProject London (Rated B-class, Top-importance)
* WikiProject Kent (Rated B-class, Top-importance)
--- This article has been reviewed by the Version 1.0 Editorial Team.
* C - This article has been rated as C-Class on the quality scale.
* B? -
This article has not yet been checked against the criteria for B-Class status:
Referencing and citation: not checked
Coverage and accuracy: not checked
Structure: not checked
Grammar and style: not checked
Supporting materials: not checked
Accessibility: not checked
To fill out this checklist, please add the following code to the template call assessing the article against each criterion.
* High - This article has been rated as High-importance on the importance scale.
https://en.wikipedia.org/wiki/Special:Preferences#mw-prefsec...
The lock icon is a different issue, it is used in a subset of controversial or high-profile articles to limit the types of editors that can edit it (from requiring editors to be logged-in to a temporary full edit block during disputes).