Displaying the number of nodes related with taxonomy terms in views block (Drupal 7), you can do the following -
1. Create a views block
2. Under fields, add taxonomy term: Name
4. Under relationships, add taxonomy terms: content with term
5. Under contextual filter, add taxonomy term: name, choose "Display a summary", "Display record count with link".
You will have views block which will display taxonomy terms with number count for example -
In the above example shoes,clothes and hats are taxonomy terms, and number in parenthesis displays the node count for that term.