Definition of en rule in English:

en rule

noun

British
  • A short dash (–) used in punctuation, in particular between figures to show a range (for example, 1939–45).

    Compare with em rule
    • ‘In print, the dash is usually represented by an em rule, although some styles favour the shorter en rule with a space on either side.’
    • ‘Do not use an en rule in place of a hyphen.’
    • ‘Use an en rule rather than a hyphen between the numbers.’

Pronunciation:

en rule

/ˈɛn ruːl/