Rules for Using Dashes

En dash

An en dash (–) is longer than a hyphen but shorter than an em dash.
Use the en dash to indicate a range of numbers (45 – 60 minutes) and include one space on each side of the dash.

Em dash

Use an em dash (—) for emphasis when appropriate, or to separate a series of nouns from a clause summarizing them. The em dash can also be used to indicate an open range, such as a date range.